diff --git a/.gitignore b/.gitignore
index 1b86803..7871689 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,6 @@
+__debug*
 /retrosheet
+test.gm
 *.pdf
 /*.csv
 /.vscode
diff --git a/20230916-1.gm b/20230916-1.gm
deleted file mode 100644
index fbde4f7..0000000
--- a/20230916-1.gm
+++ /dev/null
@@ -1,81 +0,0 @@
-date: 9/16/23
-game: 1
-visitorid: pride-jf-16u
-home: Ohana Tigers McKay
-timelimit: 80m
-tournament: Back to School Bash for Cash
----
-visitorplays
-pitching 1
-1 17 BLBSFBFFX S7/L7
-2 6 B WP 1-2
-... MBFBB W
-3 26 CBX 53/G5/B/SH 1-2 2-3
-4 11 BFX S8/G1 2-H 3-H
-5 3 BB WP 1-2
-... BSB W+SB3
-6 7 X FC1/BG1/SH B-1 1-2
-7 12 BB WP 1-2 2-3 3-H
-... SSC K
-8 21 CBSBX 43/G4
-score 3
-
-9 2 BFFBBB W
-10 18 BBBCFB W 1-2
-11 00 BBFBFX 9/L9
-12 17 BCFFBFC K
-13 6 BBX S3/G3/B 1-2 2-3
-14 26 FBBBB W 1-2 2-3 3-H
-15 11 X S8/G4 B-2 1-3(E8) 2-H 3-H
-16 3 BBCBSFS K
-score 6
-
-17 7 X S9/G4
-18 12 BB WP 1-2
-... SSFBS K
-19 21 X 63/G6 2-H(E3/TH)
-20 2 BX 43/G4
-score 7
-
-21 18 X 6/P6
-22 00 BX S8/G8
-23 17 SBLBX S7/L7 1-2
-24 6 B PB 1-2 2-3
-... BFFBFB W+WP 2-3 3-H
-25 26 CBX FC1/G1 B-1 1-3 3-H
-26 11 BX FC4/G4 B-1 1-2(E6) 3-H
-27 3 FBFFBS K
-28 7 FBBFBB W 1-2 2-3
-29 12 CFBBS K
-score 10
-
-homeplays
-pitching 11
-1 1 FSS K
-2 17 BFBBCB W
-3 11 FCX 9/F9
-4 18 BFBBFFB W 1-2
-5 5 SX S7/G6 1-3 2-H
-6 32 BX E4/P4 B-1 1-3 3-H 
-alt 4/P4 : bad positioning
-7 15 BCX 13/G1
-score 2
-
-8 14 BBFBX 9/L9
-9 7 SBSBS K
-10 16 BSFFBX 53/G5
-11 23 CFS K23
-12 20 CSS K23
-13 1 X 6/P6
-score 2
-
-14 17 BFCBX 5/L5
-15 11 X H/F7 B-H
-16 18 BSX 63/G6
-17 5 FX S7/G56
-18 32 X E5/G5/TH B-3(E9) 1-H
-alt 53/G5 1-2
-19 15 X 3/P3
-final 4
-
-
diff --git a/cmd/newgame.go b/cmd/newgame.go
index a020c2e..ef244eb 100644
--- a/cmd/newgame.go
+++ b/cmd/newgame.go
@@ -1,71 +1,10 @@
 package cmd
 
 import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"strconv"
-
 	"github.com/slshen/sb/pkg/gamefile"
 	"github.com/spf13/cobra"
 )
 
-func writeNewGame(gm *gamefile.File, nextDay bool) (*gamefile.File, error) {
-	ng := &gamefile.File{}
-	date, err := gm.GetGameDate()
-	if err != nil {
-		return nil, fmt.Errorf("%s does not have a game date - %w", gm.Path, err)
-	}
-	var numberString string
-	if nextDay {
-		date = date.AddDate(0, 0, 1)
-		numberString = "1"
-	} else {
-		number, _ := strconv.Atoi(gm.Properties["game"])
-		numberString = fmt.Sprintf("%d", number+1)
-	}
-	dateString := date.Format(gamefile.GameDateFormat)
-	for _, prop := range gm.PropertyList {
-		switch {
-		case prop.Key == "date":
-			ng.PropertyList = append(ng.PropertyList,
-				&gamefile.Property{
-					Key:   "date",
-					Value: dateString,
-				})
-		case prop.Key == "game":
-			ng.PropertyList = append(ng.PropertyList,
-				&gamefile.Property{
-					Key:   "game",
-					Value: numberString,
-				})
-		case prop.Key == "visitorid" || prop.Key == "homeid" ||
-			prop.Key == "tournament" || prop.Key == "league" ||
-			prop.Key == "timelimit":
-			ng.PropertyList = append(ng.PropertyList, prop)
-		default:
-			ng.PropertyList = append(ng.PropertyList,
-				&gamefile.Property{
-					Key: prop.Key,
-				})
-		}
-	}
-	if err := ng.Validate(); err != nil {
-		return nil, err
-	}
-	file := filepath.Join(filepath.Dir(gm.Path), fmt.Sprintf("%s-%s.gm", date.Format("20060102"), numberString))
-	fmt.Printf("Creating new game %s\n", file)
-	ng.Path = file
-	flags := os.O_CREATE | os.O_TRUNC | os.O_WRONLY | os.O_EXCL
-	f, err := os.OpenFile(file, flags, 0666)
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
-	ng.Write(f)
-	return ng, nil
-}
-
 func newGameCommand() *cobra.Command {
 	var (
 		nextDay bool
@@ -80,7 +19,7 @@ func newGameCommand() *cobra.Command {
 				return err
 			}
 			for i := 0; i < count; i++ {
-				ng, err := writeNewGame(gm, nextDay)
+				ng, err := gm.WriteNewGame(nextDay)
 				if err != nil {
 					return err
 				}
diff --git a/cmd/root.go b/cmd/root.go
index 14110dc..22cfed7 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -24,6 +24,7 @@ func Root() *cobra.Command {
 		fmtCommand(), altCommand(), webdataCommand(), newGameCommand(),
 		battingCountCommand(), battingTimesSeenPitcherCommand(),
 		pitchingTimesSeenLineupCommand(), simCommand(),
+		uiCommand(),
 	)
 	return root
 }
diff --git a/cmd/ui.go b/cmd/ui.go
new file mode 100644
index 0000000..56dfe9f
--- /dev/null
+++ b/cmd/ui.go
@@ -0,0 +1,44 @@
+package cmd
+
+import (
+	"log"
+	"os"
+
+	"github.com/slshen/sb/pkg/ui"
+	"github.com/spf13/cobra"
+)
+
+func uiCommand() *cobra.Command {
+	var (
+		debugOut string
+		re       reArgs
+	)
+	c := &cobra.Command{
+		Use:  "ui",
+		Args: cobra.MaximumNArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			var path string
+			if len(args) == 1 {
+				path = args[0]
+			}
+			ui := ui.New()
+			re, err := re.getRunExpectancy()
+			if err != nil {
+				return err
+			}
+			ui.RE = re
+			if debugOut != "" {
+				f, err := os.Create(debugOut)
+				if err != nil {
+					return err
+				}
+				defer f.Close()
+				ui.Logger = log.New(f, "", log.LstdFlags)
+			}
+			return ui.Run(path)
+		},
+	}
+	c.Flags().StringVar(&debugOut, "debug-out", "", "Write debug logs to FILE")
+	re.registerFlags(c.Flags())
+	return c
+}
diff --git a/go.mod b/go.mod
index 6c59b30..56dc9c9 100644
--- a/go.mod
+++ b/go.mod
@@ -4,10 +4,12 @@ go 1.18
 
 require (
 	github.com/alecthomas/participle/v2 v2.1.0
+	github.com/gdamore/tcell/v2 v2.7.1
 	github.com/hashicorp/go-multierror v1.1.1
 	github.com/kr/text v0.2.0
 	github.com/mitchellh/go-wordwrap v1.0.1
 	github.com/mitchellh/mapstructure v1.5.0
+	github.com/rivo/tview v0.0.0-20240921122403-a64fc48d7654
 	github.com/spf13/cobra v1.7.0
 	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.8.4
@@ -16,9 +18,16 @@ require (
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/gdamore/encoding v1.0.0 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
+	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
+	github.com/mattn/go-runewidth v0.0.15 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	golang.org/x/sys v0.17.0 // indirect
+	golang.org/x/term v0.17.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 )
diff --git a/go.sum b/go.sum
index e90516a..8c98b97 100644
--- a/go.sum
+++ b/go.sum
@@ -6,6 +6,10 @@ github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46t
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdko=
+github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
+github.com/gdamore/tcell/v2 v2.7.1 h1:TiCcmpWHiAU7F0rA2I3S2Y4mmLmO9KHxJ7E1QhYzQbc=
+github.com/gdamore/tcell/v2 v2.7.1/go.mod h1:dSXtXTSK0VsW1biw65DZLZ2NKr7j0qP/0J7ONmsraWg=
 github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/errwrap v1.1.0 h1:OxrOeh75EUXMY8TBjag2fzXGZ40LB6IKw45YeGUDY2I=
 github.com/hashicorp/errwrap v1.1.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
@@ -21,6 +25,10 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
+github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
+github.com/mattn/go-runewidth v0.0.15 h1:UNAjwbU9l54TA3KzvqLGxwWjHmMgBUVhBiTjelZgg3U=
+github.com/mattn/go-runewidth v0.0.15/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
 github.com/mitchellh/go-wordwrap v1.0.1 h1:TLuKupo69TCn6TQSyGxwI1EblZZEsQ0vMlAFQflz0v0=
 github.com/mitchellh/go-wordwrap v1.0.1/go.mod h1:R62XHJLzvMFRBbcrT7m7WgmE1eOyTSsCt+hzestvNj0=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
@@ -28,6 +36,12 @@ github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RR
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rivo/tview v0.0.0-20240921122403-a64fc48d7654 h1:oa+fljZiaJUVyiT7WgIM3OhirtwBm0LJA97LvWUlBu8=
+github.com/rivo/tview v0.0.0-20240921122403-a64fc48d7654/go.mod h1:02iFIz7K/A9jGCvrizLPvoqr4cEIx7q54RH5Qudkrss=
+github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
+github.com/rivo/uniseg v0.4.3/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
+github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
+github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
@@ -37,6 +51,42 @@ github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
+golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
+golang.org/x/term v0.17.0 h1:mkTF7LCd6WGJNL3K1Ad7kwxNfYAW6a8a8QqtMblp/4U=
+golang.org/x/term v0.17.0/go.mod h1:lLRBjIVuehSbZlaOtGMbcMncT+aqLLLmKrsjNrUguwk=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
diff --git a/pkg/dataframe/data.go b/pkg/dataframe/data.go
index df8ab86..86792cd 100644
--- a/pkg/dataframe/data.go
+++ b/pkg/dataframe/data.go
@@ -34,11 +34,7 @@ func FromStructs(name string, values interface{}) (*Data, error) {
 	var idx *Index
 	for i := 0; i < v.Len(); i++ {
 		val := v.Index(i).Interface()
-		var err error
 		idx = dat.AppendStruct(idx, val)
-		if err != nil {
-			return nil, err
-		}
 	}
 	return dat, nil
 }
@@ -141,6 +137,15 @@ func (dat *Data) RApply(f func(row int)) {
 	}
 }
 
+func (dat *Data) GetColumn(name string) *Column {
+	for _, col := range dat.Columns {
+		if col.Name == name {
+			return col
+		}
+	}
+	return nil
+}
+
 func (dat *Data) GetRow(r int) []interface{} {
 	row := make([]interface{}, len(dat.Columns))
 	for i, col := range dat.Columns {
diff --git a/pkg/game/advance.go b/pkg/game/advance.go
index a15b9f3..ef0ad34 100644
--- a/pkg/game/advance.go
+++ b/pkg/game/advance.go
@@ -1,7 +1,6 @@
 package game
 
 import (
-	"fmt"
 	"regexp"
 
 	"github.com/slshen/sb/pkg/gamefile"
@@ -53,7 +52,7 @@ func (a *Advance) GoString() string {
 func parseAdvance(play gamefile.Play, s string) (*Advance, error) {
 	m := advanceRegexp.FindStringSubmatch(s)
 	if m == nil {
-		return nil, fmt.Errorf("%s: illegal advance code %s", play.GetPos(), s)
+		return nil, NewError("illegal advance code %s", play.GetPos(), s)
 	}
 	a := &Advance{
 		Code: s,
@@ -70,12 +69,12 @@ func parseAdvance(play gamefile.Play, s string) (*Advance, error) {
 				if f >= '1' && f <= '9' {
 					a.Fielders = append(a.Fielders, int(f-'1')+1)
 				} else {
-					return nil, fmt.Errorf("%s: illegal fielder %c for put out in advance code %s",
+					return nil, NewError("illegal fielder %c for put out in advance code %s",
 						play.GetPos(), f, s)
 				}
 			}
 			if len(a.Fielders) == 0 {
-				return nil, fmt.Errorf("%s: no fielders for put out in advancde code %s",
+				return nil, NewError("no fielders for put out in advancde code %s",
 					play.GetPos(), s)
 			}
 		}
@@ -110,20 +109,20 @@ func parseAdvances(play gamefile.Play, batter PlayerID, runners [3]PlayerID) (ad
 			return
 		}
 		if advances.From(advance.From) != nil {
-			err = fmt.Errorf("%s: cannot advance %s twice in %s", play.GetPos(), advance.From, as)
+			err = NewError("cannot advance %s twice in %s", play.GetPos(), advance.From, as)
 			return
 		}
 		if advance.From == "B" {
 			advance.Runner = batter
 		} else {
 			/*if runners == nil {
-				err = fmt.Errorf("%s: no runner to advance from %s at the start of a half-inning",
+				err = NewError("no runner to advance from %s at the start of a half-inning",
 					play.GetPos(), advance.From)
 				return
 			}*/
 			advance.Runner = runners[runnerNumber[advance.From]]
 			if advance.Runner == "" {
-				err = fmt.Errorf("%s: no runner to advance from %s in %s", play.GetPos(),
+				err = NewError("no runner to advance from %s in %s", play.GetPos(),
 					advance.From, as)
 				return
 			}
diff --git a/pkg/game/error.go b/pkg/game/error.go
new file mode 100644
index 0000000..70df737
--- /dev/null
+++ b/pkg/game/error.go
@@ -0,0 +1,23 @@
+package game
+
+import (
+	"fmt"
+
+	"github.com/slshen/sb/pkg/gamefile"
+)
+
+type Error struct {
+	Pos     gamefile.Position
+	Message string
+}
+
+func NewError(template string, pos gamefile.Position, args ...any) Error {
+	return Error{
+		Pos:     pos,
+		Message: fmt.Sprintf("%s: %s", pos, fmt.Sprintf(template, args...)),
+	}
+}
+
+func (e Error) Error() string { return e.Message }
+
+func (e Error) Position() gamefile.Position { return e.Pos }
diff --git a/pkg/game/fieldingerror.go b/pkg/game/fieldingerror.go
index 4552d57..efb5d7f 100644
--- a/pkg/game/fieldingerror.go
+++ b/pkg/game/fieldingerror.go
@@ -16,10 +16,10 @@ var NoError = FieldingError{}
 
 func parseFieldingError(play gamefile.Play, s string) (FieldingError, error) {
 	if len(s) < 2 || s[0] != 'E' || (len(s) > 2 && s[2] != '/') {
-		return FieldingError{}, fmt.Errorf("%s: illegal error code %s", play.GetPos(), s)
+		return FieldingError{}, NewError("illegal error code %s", play.GetPos(), s)
 	}
 	if s[1] < '1' || s[1] > '9' {
-		return FieldingError{}, fmt.Errorf("%s: illegal fielder %c in error code %s", play.GetPos(), s[1], s)
+		return FieldingError{}, NewError("illegal fielder %c in error code %s", play.GetPos(), s[1], s)
 	}
 	fe := FieldingError{
 		Fielder: int(s[1] - '0'),
diff --git a/pkg/game/game.go b/pkg/game/game.go
index d0ca7da..72110b9 100644
--- a/pkg/game/game.go
+++ b/pkg/game/game.go
@@ -1,7 +1,6 @@
 package game
 
 import (
-	"fmt"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -146,10 +145,10 @@ func ReadGameFile(path string) (*Game, error) {
 	if err != nil {
 		return nil, err
 	}
-	return newGame(gf)
+	return NewGame(gf)
 }
 
-func newGame(gf *gamefile.File) (*Game, error) {
+func NewGame(gf *gamefile.File) (*Game, error) {
 	g := &Game{
 		File:       gf,
 		Tournament: gf.Properties["tournament"],
@@ -251,7 +250,7 @@ func (g *Game) runPlays(battingTeam, fieldingTeam *Team, half Half, events []*ga
 	if events == nil {
 		return
 	}
-	m := newGameMachine(half, battingTeam, fieldingTeam)
+	m := newGameMachine(battingTeam, fieldingTeam)
 	lastState := &State{
 		InningNumber: 1,
 		Half:         half,
@@ -262,7 +261,7 @@ func (g *Game) runPlays(battingTeam, fieldingTeam *Team, half Half, events []*ga
 		}
 		if m.final {
 			errs = multierror.Append(errs,
-				fmt.Errorf("%s: cannot have more plays after final score", event.Pos))
+				NewError("cannot have more plays after final score", event.Pos))
 			break
 		}
 		switch {
@@ -297,7 +296,7 @@ func (g *Game) runPlays(battingTeam, fieldingTeam *Team, half Half, events []*ga
 				state.Comment = event.Alternative.Comment
 				if g.altStates[lastState] != nil {
 					errs = multierror.Append(errs,
-						fmt.Errorf("%s: only a single alternate state is allowed", event.Pos))
+						NewError("only a single alternate state is allowed", event.Pos))
 				} else {
 					g.altStates[lastState] = state
 				}
diff --git a/pkg/game/gamemachine.go b/pkg/game/gamemachine.go
index 7bda126..d55cb40 100644
--- a/pkg/game/gamemachine.go
+++ b/pkg/game/gamemachine.go
@@ -19,7 +19,7 @@ type gameMachine struct {
 	modifiers    Modifiers
 }
 
-func newGameMachine(half Half, battingTeam, fieldingTeam *Team) *gameMachine {
+func newGameMachine(battingTeam, fieldingTeam *Team) *gameMachine {
 	m := &gameMachine{
 		battingTeam:  battingTeam,
 		fieldingTeam: fieldingTeam,
@@ -74,7 +74,7 @@ func (m *gameMachine) handleActualPlay(play *gamefile.ActualPlay, lastState *Sta
 	state.PlateAppearance.Number = play.PlateAppearance.Int()
 	if play.ContinuedPlateAppearance {
 		if state.LastState == nil {
-			return nil, fmt.Errorf("%s: ... can only be used to continue a plate appearance", play.GetPos())
+			return nil, NewError("... can only be used to continue a plate appearance", play.GetPos())
 		}
 		state.Pitches = state.LastState.Pitches + Pitches(play.PitchSequence)
 		state.Batter = state.LastState.Batter
@@ -83,7 +83,7 @@ func (m *gameMachine) handleActualPlay(play *gamefile.ActualPlay, lastState *Sta
 		state.Pitches = Pitches(play.PitchSequence)
 	}
 	if state.Batter == "" {
-		return nil, fmt.Errorf("%s: no batter for %s", play.GetPos(), play.GetCode())
+		return nil, NewError("no batter for %s", play.GetPos(), play.GetCode())
 	}
 	err := m.handlePlay(play, state)
 	return state, err
@@ -93,7 +93,7 @@ func (m *gameMachine) handlePlay(play gamefile.Play, state *State) error {
 	state.PlayCode = play.GetCode()
 	state.AdvancesCodes = play.GetAdvances()
 	if state.PlayCode == "" {
-		return fmt.Errorf("%s: empty event code in %s", play.GetPos(), play.GetCode())
+		return NewError("empty event code in %s", play.GetPos(), play.GetCode())
 	}
 	m.basePutOuts = nil
 	if err := m.parseAdvances(play, state); err != nil {
@@ -115,32 +115,32 @@ func (m *gameMachine) handlePlay(play gamefile.Play, state *State) error {
 		_, balls, strikes := state.Pitches.Count()
 		if state.Play.IsBallInPlay() {
 			if strikes > 2 {
-				return fmt.Errorf("%s: cannot put ball in play with %d strikes (%s)", state.Pos, strikes, play.GetCode())
+				return NewError("cannot put ball in play with %d strikes (%s)", state.Pos, strikes, play.GetCode())
 			}
 			if balls > 3 {
-				return fmt.Errorf("%s: cannot put ball in play with %d balls (%s)", state.Pos, balls, play.GetCode())
+				return NewError("cannot put ball in play with %d balls (%s)", state.Pos, balls, play.GetCode())
 			}
 		}
 		if state.Play.IsStrikeOut() {
 			if state.Pitches[len(state.Pitches)-1] == 'X' {
-				return fmt.Errorf("%s: strike out pitch sequence should not end in X", state.Pos)
+				return NewError("strike out pitch sequence should not end in X", state.Pos)
 			}
 			if strikes != 3 {
-				return fmt.Errorf("%s: must strike out with 3 strikes", state.Pos)
+				return NewError("must strike out with 3 strikes", state.Pos)
 			}
 			if balls > 3 {
-				return fmt.Errorf("%s: cannot strike out with more than 3 balls", state.Pos)
+				return NewError("cannot strike out with more than 3 balls", state.Pos)
 			}
 		}
 		if state.Play.IsWalk() {
 			if state.Pitches[len(state.Pitches)-1] == 'X' {
-				return fmt.Errorf("%s: walk pitch sequence should not end in X", state.Pos)
+				return NewError("walk pitch sequence should not end in X", state.Pos)
 			}
 			if strikes > 2 {
-				return fmt.Errorf("%s: cannot walk with more than 2 strikes", state.Pos)
+				return NewError("cannot walk with more than 2 strikes", state.Pos)
 			}
 			if balls != 4 {
-				return fmt.Errorf("%s: must walk with 4 balls", state.Pos)
+				return NewError("must walk with 4 balls", state.Pos)
 			}
 		}
 		if !strings.HasSuffix(string(state.Pitches), "X") &&
@@ -169,19 +169,19 @@ func (m *gameMachine) handleSpecialEvent(event *gamefile.Event, state *State) (*
 	}
 	if event.Score != "" {
 		if state.Outs != 3 {
-			return nil, fmt.Errorf("%s: the inning with %d outs has not ended after %s",
+			return nil, NewError("the inning with %d outs has not ended after %s",
 				event.Pos, state.Outs, state.PlayCode)
 		}
 		score, err := strconv.Atoi(event.Score)
 		if err != nil || state.Score != score {
-			return nil, fmt.Errorf("%s: in inning %d # runs is %d not %s", event.Pos,
+			return nil, NewError("in inning %d # runs is %d not %s", event.Pos,
 				state.InningNumber, state.Score, event.Score)
 		}
 	}
 	if event.Final != "" {
 		score, err := strconv.Atoi(event.Final)
 		if err != nil || state.Score != score {
-			return nil, fmt.Errorf("%s: in inning %d final score is %d not %s", event.Pos,
+			return nil, NewError("in inning %d final score is %d not %s", event.Pos,
 				state.InningNumber, state.Score, event.Score)
 		}
 		m.final = true
@@ -190,10 +190,10 @@ func (m *gameMachine) handleSpecialEvent(event *gamefile.Event, state *State) (*
 		runner := m.battingTeam.parsePlayerID(event.RAdjRunner.String())
 		base := event.RAdjBase
 		if runner == "" || !(base == "1" || base == "2" || base == "3") {
-			return nil, fmt.Errorf("%s: invalid base %s for radj", event.Pos, event.RAdjBase)
+			return nil, NewError("invalid base %s for radj", event.Pos, event.RAdjBase)
 		}
 		if state.Outs != 3 {
-			return nil, fmt.Errorf("%s: radj must be at the inning start", event.Pos)
+			return nil, NewError("radj must be at the inning start", event.Pos)
 		}
 		lastState := &State{
 			InningNumber: state.InningNumber + 1,
@@ -245,7 +245,7 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 				}
 			}
 			if !ok {
-				return fmt.Errorf("%s: cannot score SacrificeFly unless a runner scores", play.GetPos())
+				return NewError("cannot score SacrificeFly unless a runner scores", play.GetPos())
 			}
 		}
 		state.recordOut()
@@ -288,11 +288,11 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 	case pp.playIs("K+PO%($$)") || pp.playIs("K+PO%(E$)"):
 		from := pp.playMatches[0]
 		if !(from == "1" || from == "2" || from == "3") {
-			return fmt.Errorf("%s: illegal picked off base in %s", play.GetPos(), pp.playCode)
+			return NewError("illegal picked off base in %s", play.GetPos(), pp.playCode)
 		}
 		_, err := state.GetBaseRunner(from)
 		if err != nil {
-			return fmt.Errorf("%s: cannot pick off in %s - %w", play.GetPos(), pp.playCode, err)
+			return NewError("cannot pick off in %s - %w", play.GetPos(), pp.playCode, err)
 		}
 		state.Play = Play{
 			Type: StrikeOutPickedOff,
@@ -311,7 +311,7 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 				state.recordOut()
 				m.putOut(from)
 			} else {
-				return fmt.Errorf("%s: picked off runner on %s cannot advance", play.GetPos(), from)
+				return NewError("picked off runner on %s cannot advance", play.GetPos(), from)
 			}
 		}
 	case pp.playIs("W+WP"):
@@ -426,7 +426,7 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 	case pp.playIs("E$"):
 		fe, err := parseFieldingError(play, pp.playCode)
 		if err != nil {
-			return fmt.Errorf("%s: cannot parse fielding error in %s - %w", play.GetPos(),
+			return NewError("cannot parse fielding error in %s - %w", play.GetPos(),
 				pp.playCode, err)
 		}
 		state.Play = Play{
@@ -446,7 +446,7 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 			}
 		}
 		if fielder == 0 {
-			return fmt.Errorf("%s: no fielder in catcher's interference", play.GetPos())
+			return NewError("no fielder in catcher's interference", play.GetPos())
 		}
 		state.Play = Play{
 			Type: CatcherInterference,
@@ -482,7 +482,7 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 	case pp.playIs("$(B)$(%)") || pp.playIs("$(B)$$(%)") ||
 		pp.playIs("$(B)$$$(%)"):
 		if !m.modifiers.Contains("LDP", "FDP") {
-			return fmt.Errorf("%s: play should contain LDP or FDP modifier in %s (%v)",
+			return NewError("play should contain LDP or FDP modifier in %s (%v)",
 				play.GetPos(), pp.playCode, state.Modifiers)
 		}
 		base := pp.playMatches[len(pp.playMatches)-1]
@@ -519,25 +519,25 @@ func (m *gameMachine) handlePlayCode(play gamefile.Play, state *State) error {
 		}
 		// no play
 	default:
-		return fmt.Errorf("%s: unknown play %s", play.GetPos(), play.GetCode())
+		return NewError("unknown play %s", play.GetPos(), play.GetCode())
 	}
 	return nil
 }
 
 func (m *gameMachine) handleGroundBallDoublePlay(play gamefile.Play, state *State, pp playCodeParser, runnerBase string) error {
 	if !m.modifiers.Contains("GDP") {
-		return fmt.Errorf("%s: play should contain GDP modifier in %s", play.GetPos(), pp.playCode)
+		return NewError("play should contain GDP modifier in %s", play.GetPos(), pp.playCode)
 	}
 	_, err := state.GetBaseRunner(runnerBase)
 	if err != nil {
-		return fmt.Errorf("%s: no runner in double play %s - %w", play.GetPos(), pp.playCode, err)
+		return NewError("no runner in double play %s - %w", play.GetPos(), pp.playCode, err)
 	}
 	state.Play = Play{
 		Type: DoublePlay,
 	}
 	nextBase := NextBase[runnerBase]
 	if nextBase == "" {
-		return fmt.Errorf("%s: double play runner cannot be at %s", play.GetPos(), runnerBase)
+		return NewError("double play runner cannot be at %s", play.GetPos(), runnerBase)
 	}
 	paren := strings.IndexRune(pp.playCode, '(')
 	fielders := pp.playCode[0:paren]
@@ -558,7 +558,7 @@ func (m *gameMachine) handleCaughtStealing(play gamefile.Play, state *State, pp
 	advance := state.Advances.From(from)
 	runner, err := state.GetBaseRunner(from)
 	if err != nil {
-		return fmt.Errorf("%s: cannot catch stealing runner in %s - %w", play.GetPos(), pp.playCode, err)
+		return NewError("cannot catch stealing runner in %s - %w", play.GetPos(), pp.playCode, err)
 	}
 	state.Play = Play{
 		Type:                 CaughtStealing,
@@ -578,11 +578,11 @@ func (m *gameMachine) handleCaughtStealing(play gamefile.Play, state *State, pp
 func (m *gameMachine) handlePickedoff(play gamefile.Play, state *State, pp playCodeParser, playType PlayType, fieldingError FieldingError) error {
 	from := pp.playMatches[0]
 	if !(from == "1" || from == "2" || from == "3") {
-		return fmt.Errorf("%s: illegal picked off base %s", play.GetPos(), from)
+		return NewError("illegal picked off base %s", play.GetPos(), from)
 	}
 	runner, err := state.GetBaseRunner(from)
 	if err != nil {
-		return fmt.Errorf("%s: cannot pick off runner - %w", play.GetPos(), err)
+		return NewError("cannot pick off runner - %w", play.GetPos(), err)
 	}
 	state.Play = Play{
 		Type:            playType,
@@ -601,7 +601,7 @@ func (m *gameMachine) handlePickedoff(play gamefile.Play, state *State, pp playC
 
 func (m *gameMachine) handleStolenBase(play gamefile.Play, state *State, eventMatches []string) error {
 	if state.LastState == nil {
-		return fmt.Errorf("%s: cannot steal bases at the start of a half-inning", play.GetPos())
+		return NewError("cannot steal bases at the start of a half-inning", play.GetPos())
 	}
 	for i := range eventMatches {
 		base := eventMatches[i]
@@ -620,13 +620,13 @@ func (m *gameMachine) handleStolenBase(play gamefile.Play, state *State, eventMa
 			adv = m.impliedAdvance(play, state, "3-H")
 			runner = state.LastState.Runners[2]
 		default:
-			return fmt.Errorf("%s: unknown stolen base code", play.GetPos())
+			return NewError("unknown stolen base code", play.GetPos())
 		}
 		adv.Runner = runner
 		adv.Steal = true
 		state.Play.StolenBases = append(state.Play.StolenBases, base)
 		if runner == "" {
-			return fmt.Errorf("%s: no runner can steal %s", play.GetPos(), base)
+			return NewError("no runner can steal %s", play.GetPos(), base)
 		}
 	}
 	return nil
@@ -656,10 +656,10 @@ func (m *gameMachine) moveRunners(play gamefile.Play, state *State) error {
 		to := BaseNumber[advance.To]
 		switch {
 		case state.LastState == nil && advance.From != "B":
-			return fmt.Errorf("%s: cannot advance a runner from %s to %s at start of half-inning",
+			return NewError("cannot advance a runner from %s to %s at start of half-inning",
 				play.GetPos(), advance.From, advance.To)
 		case advance.From != "B" && state.LastState != nil && state.LastState.Runners[from] == "":
-			return fmt.Errorf("%s: cannot advance non-existent runner from %s",
+			return NewError("cannot advance non-existent runner from %s",
 				play.GetPos(), advance.From)
 		case advance.Out:
 			state.recordOut()
@@ -674,13 +674,13 @@ func (m *gameMachine) moveRunners(play gamefile.Play, state *State) error {
 			}
 		case advance.From == "B":
 			if state.Runners[to] != "" && !isFieldersChoice3rdOut(state) {
-				return fmt.Errorf("%s: cannot advance batter-runner %s to %d because it's already occupied by %s",
+				return NewError("cannot advance batter-runner %s to %d because it's already occupied by %s",
 					play.GetPos(), state.Batter, to+1, state.Runners[to])
 			}
 			state.Runners[to] = state.Batter
 		default:
 			if state.Runners[to] != "" && !isFieldersChoice3rdOut(state) {
-				return fmt.Errorf("%s: cannot advance runner %s to %d because it's already occupied by %s",
+				return NewError("cannot advance runner %s to %d because it's already occupied by %s",
 					play.GetPos(), state.LastState.Runners[from], to+1, state.Runners[to])
 			}
 			state.Runners[to] = state.LastState.Runners[from]
diff --git a/pkg/game/state.go b/pkg/game/state.go
index 272f6eb..adcd07f 100644
--- a/pkg/game/state.go
+++ b/pkg/game/state.go
@@ -4,14 +4,13 @@ import (
 	"fmt"
 	"regexp"
 	"strings"
+
+	"github.com/slshen/sb/pkg/gamefile"
 )
 
 type Pitches string
 type PlayerID string
-type FileLocation struct {
-	Filename string
-	Line     int
-}
+type FileLocation = gamefile.Position
 
 type Half string
 
@@ -50,10 +49,6 @@ type PlateAppearance struct {
 	Modifiers  `yaml:",omitempty,flow"`
 }
 
-func (pos FileLocation) String() string {
-	return fmt.Sprintf("%s:%d", pos.Filename, pos.Line)
-}
-
 func (state *State) Top() bool {
 	return state.Half == Top
 }
@@ -69,16 +64,16 @@ func (state *State) GetRunsScored() int {
 
 func (state *State) GetBaseRunner(base string) (runner PlayerID, err error) {
 	if base == "H" {
-		err = fmt.Errorf("a runner cannot be at H")
+		err = NewError("a runner cannot be at H", state.Pos)
 		return
 	}
 	if state.LastState == nil || (state.LastState.InningNumber != state.InningNumber) {
-		err = fmt.Errorf("no runners are on base at the start of a half-inning")
+		err = NewError("no runners are on base at the start of a half-inning", state.Pos)
 		return
 	}
 	runner = state.LastState.Runners[runnerNumber[base]]
 	if runner == "" {
-		err = fmt.Errorf("no runner on %s", base)
+		err = NewError("no runner on %s", state.Pos, base)
 	}
 	return
 }
diff --git a/pkg/gamefile/file.go b/pkg/gamefile/file.go
index c7912d1..d278d4b 100644
--- a/pkg/gamefile/file.go
+++ b/pkg/gamefile/file.go
@@ -34,7 +34,7 @@ type TeamEvents struct {
 type Property struct {
 	Pos   Position
 	Key   string `parser:"@Ident"`
-	Value string `parser:"@Text (NL|EOF)"`
+	Value string `parser:"@Text (NL+|EOF)"`
 }
 
 type Event struct {
@@ -101,6 +101,10 @@ func (n Numbers) Int() int {
 	return i
 }
 
+func (f *File) Parse(r io.Reader) error {
+	return nil
+}
+
 func (f *File) Validate() error {
 	f.Properties = make(map[string]string)
 	f.PropertyPos = make(map[string]Position)
diff --git a/pkg/gamefile/newgame.go b/pkg/gamefile/newgame.go
new file mode 100644
index 0000000..a5afa23
--- /dev/null
+++ b/pkg/gamefile/newgame.go
@@ -0,0 +1,61 @@
+package gamefile
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+)
+
+func (f *File) WriteNewGame(nextDay bool) (*File, error) {
+	ng := &File{}
+	date, err := f.GetGameDate()
+	if err != nil {
+		return nil, fmt.Errorf("%s does not have a game date - %w", f.Path, err)
+	}
+	var numberString string
+	if nextDay {
+		date = date.AddDate(0, 0, 1)
+		numberString = "1"
+	} else {
+		number, _ := strconv.Atoi(f.Properties["game"])
+		numberString = fmt.Sprintf("%d", number+1)
+	}
+	dateString := date.Format(GameDateFormat)
+	for _, prop := range f.PropertyList {
+		switch {
+		case prop.Key == "date":
+			ng.PropertyList = append(ng.PropertyList,
+				&Property{
+					Key:   "date",
+					Value: dateString,
+				})
+		case prop.Key == "game":
+			ng.PropertyList = append(ng.PropertyList,
+				&Property{
+					Key:   "game",
+					Value: numberString,
+				})
+		case prop.Key == "visitorid" || prop.Key == "homeid" ||
+			prop.Key == "tournament" || prop.Key == "league" ||
+			prop.Key == "timelimit":
+			ng.PropertyList = append(ng.PropertyList, prop)
+		default:
+			ng.PropertyList = append(ng.PropertyList,
+				&Property{
+					Key: prop.Key,
+				})
+		}
+	}
+	if err := ng.Validate(); err != nil {
+		return nil, err
+	}
+	file := filepath.Join(filepath.Dir(f.Path), fmt.Sprintf("%s-%s.gm", date.Format("20060102"), numberString))
+	ng.Path = file
+	fd, err := os.Create(file)
+	if err != nil {
+		return nil, err
+	}
+	ng.Write(fd)
+	return ng, fd.Close()
+}
diff --git a/pkg/gamefile/parser.go b/pkg/gamefile/parser.go
index 98583fb..5183aee 100644
--- a/pkg/gamefile/parser.go
+++ b/pkg/gamefile/parser.go
@@ -6,7 +6,16 @@ import (
 	"github.com/alecthomas/participle/v2"
 )
 
-var parser = participle.MustBuild[File](participle.Lexer(gameFileDef))
+var Parser = participle.MustBuild[File](participle.Lexer(gameFileDef))
+
+func ParseString(path string, text string) (*File, error) {
+	file, err := Parser.ParseString(path, text)
+	if err == nil {
+		file.Path = path
+		err = file.Validate()
+	}
+	return file, err
+}
 
 func ParseFile(path string) (*File, error) {
 	f, err := os.Open(path)
@@ -14,7 +23,7 @@ func ParseFile(path string) (*File, error) {
 		return nil, err
 	}
 	defer f.Close()
-	file, err := parser.Parse(path, f)
+	file, err := Parser.Parse(path, f)
 	if err != nil {
 		return nil, err
 	}
diff --git a/pkg/gamefile/parser_test.go b/pkg/gamefile/parser_test.go
index c226208..3c128cb 100644
--- a/pkg/gamefile/parser_test.go
+++ b/pkg/gamefile/parser_test.go
@@ -8,7 +8,7 @@ import (
 
 func TestParser(t *testing.T) {
 	assert := assert.New(t)
-	assert.NotNil(parser)
+	assert.NotNil(Parser)
 	f, err := ParseFile("testdata/test.gm")
 	if !assert.NoError(err) {
 		return
diff --git a/pkg/ui/chooser.go b/pkg/ui/chooser.go
new file mode 100644
index 0000000..1ab21d0
--- /dev/null
+++ b/pkg/ui/chooser.go
@@ -0,0 +1,79 @@
+package ui
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/gdamore/tcell/v2"
+	"github.com/rivo/tview"
+)
+
+type Chooser struct {
+	*tview.Grid
+	done  func(string, bool)
+	dir   string
+	files []string
+}
+
+func NewChooser(dir string, name string, done func(string, bool)) *Chooser {
+	c := &Chooser{
+		Grid: tview.NewGrid(),
+		done: done,
+		dir:  dir,
+	}
+	files, index := listGameFiles(dir, name)
+	c.files = files
+	list := tview.NewList().
+		ShowSecondaryText(false).
+		SetSelectedFunc(c.selectFile)
+	list.SetBorder(true).SetTitle("Choose a game (ESC closes)")
+	list.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+		if event.Key() == tcell.KeyEscape {
+			c.done("", false)
+			return nil
+		}
+		return event
+	})
+	for _, file := range files {
+		list.AddItem(file, "", 0, nil)
+	}
+	list.AddItem("<new game>", "", 0, nil)
+	if index >= 0 {
+		list.SetCurrentItem(index)
+	}
+	c.SetColumns(2, 0, 2).SetRows(2, 0, 2).AddItem(list, 1, 1, 1, 1, 0, 0, true)
+	return c
+}
+
+func (c *Chooser) selectFile(i int, _ string, _ string, _ rune) {
+	switch {
+	case i < len(c.files):
+		c.done(path.Join(c.dir, c.files[i]), false)
+	case len(c.files) == 0:
+		c.done(path.Join(c.dir, fmt.Sprintf("%s-1.gm", time.Now().Format("20060102"))), false)
+	default:
+		c.done(path.Join(c.dir, c.files[len(c.files)-1]), true)
+	}
+}
+
+func listGameFiles(dir string, name string) (result []string, index int) {
+	entries, _ := os.ReadDir(dir)
+	for _, entry := range entries {
+		if !entry.IsDir() && strings.HasSuffix(entry.Name(), ".gm") {
+			result = append(result, entry.Name())
+		}
+	}
+	sort.Strings(result)
+	index = -1
+	for i := range result {
+		if result[i] == name {
+			index = i
+			break
+		}
+	}
+	return
+}
diff --git a/pkg/ui/lines.go b/pkg/ui/lines.go
new file mode 100644
index 0000000..1a79c3c
--- /dev/null
+++ b/pkg/ui/lines.go
@@ -0,0 +1,51 @@
+package ui
+
+import (
+	"github.com/gdamore/tcell/v2"
+	"github.com/rivo/tview"
+)
+
+// TextArea doesn't provide GetSelectedStyle() so just assume it's the default
+var defaultSelectedStyle = tcell.StyleDefault.Background(tview.Styles.PrimaryTextColor).
+	Foreground(tview.Styles.PrimitiveBackgroundColor)
+
+type LinedTextArea struct {
+	*tview.TextArea
+	LineColors map[int]*tcell.Color
+}
+
+func NewLinedtextArea() *LinedTextArea {
+	t := &LinedTextArea{
+		TextArea:   tview.NewTextArea(),
+		LineColors: map[int]*tcell.Color{},
+	}
+	return t
+}
+
+func (t *LinedTextArea) ClearColors() {
+	for k := range t.LineColors {
+		delete(t.LineColors, k)
+	}
+}
+
+func (t *LinedTextArea) Draw(screen tcell.Screen) {
+	t.TextArea.Draw(screen)
+	firstLine, _ := t.GetOffset()
+	x, y, width, height := t.GetInnerRect()
+	for row := y; row < y+height; row++ {
+		line := firstLine + row - y
+		lineColor := t.LineColors[line]
+		if lineColor != nil {
+			for col := x; col < x+width; {
+				ch, chc, chStyle, chw := screen.GetContent(col, row)
+				if chStyle == defaultSelectedStyle {
+					chStyle = chStyle.Foreground(*lineColor)
+				} else {
+					chStyle = chStyle.Background(*lineColor)
+				}
+				screen.SetContent(col, row, ch, chc, chStyle)
+				col += chw
+			}
+		}
+	}
+}
diff --git a/pkg/ui/ui.go b/pkg/ui/ui.go
new file mode 100644
index 0000000..eb59785
--- /dev/null
+++ b/pkg/ui/ui.go
@@ -0,0 +1,466 @@
+package ui
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/gdamore/tcell/v2"
+	"github.com/hashicorp/go-multierror"
+	"github.com/rivo/tview"
+	"github.com/slshen/sb/pkg/boxscore"
+	"github.com/slshen/sb/pkg/game"
+	"github.com/slshen/sb/pkg/gamefile"
+	"github.com/slshen/sb/pkg/stats"
+)
+
+type UI struct {
+	Logger            *log.Logger
+	RE                stats.RunExpectancy
+	path              string
+	app               *tview.Application
+	root              *tview.Pages
+	box               *tview.TextView
+	properties        *LinedTextArea
+	visitorPlaysStart int
+	visitorPlays      *LinedTextArea
+	homePlaysStart    int
+	homePlays         *LinedTextArea
+	messages          *tview.TextView
+	lastKey           time.Time
+	lastUpdate        time.Time
+	focusOrder        []tview.Primitive
+	status            *tview.TextView
+	dialog            tview.Primitive
+	modified          bool
+}
+
+var errorColor = tcell.ColorBlue
+
+func New() *UI {
+	ui := &UI{
+		Logger:       log.New(io.Discard, "", 0),
+		app:          tview.NewApplication(),
+		root:         tview.NewPages(),
+		properties:   NewLinedtextArea(),
+		visitorPlays: NewLinedtextArea(),
+		homePlays:    NewLinedtextArea(),
+		box:          tview.NewTextView(),
+		messages:     tview.NewTextView().SetDynamicColors(true),
+		status:       tview.NewTextView().SetTextAlign(tview.AlignRight),
+	}
+	for _, box := range []any{ui.properties, ui.box, ui.visitorPlays, ui.homePlays, ui.messages} {
+		box.(interface{ SetBorder(bool) *tview.Box }).SetBorder(true)
+	}
+	ui.focusOrder = []tview.Primitive{ui.properties, ui.visitorPlays, ui.homePlays}
+	flex := tview.NewFlex().SetDirection(tview.FlexRow)
+	flex.AddItem(tview.NewFlex().
+		AddItem(ui.properties, 0, 1, true).
+		AddItem(ui.box, 0, 1, false),
+		7, 0, true)
+	flex.AddItem(tview.NewFlex().
+		AddItem(ui.visitorPlays, 0, 1, false).
+		AddItem(ui.homePlays, 0, 1, false),
+		0, 1, false).
+		AddItem(ui.messages, 6, 0, false).
+		AddItem(tview.NewFlex().
+			AddItem(tview.NewTextView().SetText("Quit:^Q Save:^S Choose:^L"), 0, 4, false).
+			AddItem(ui.status, 0, 1, false),
+			1, 0, false)
+	ui.root.AddAndSwitchToPage("main", flex, true)
+	ui.app.
+		EnableMouse(true).
+		SetRoot(ui.root, true).
+		SetInputCapture(ui.inputHandler)
+	return ui
+}
+
+func (ui *UI) update() {
+	t0 := time.Now()
+	var text string
+	ui.app.QueueUpdate(func() {
+		text = ui.getGameText()
+	})
+	file, err := gamefile.ParseString(ui.path, text)
+	var (
+		msg      string
+		boxScore string
+		gm       *game.Game
+	)
+	if err != nil {
+		msg = err.Error()
+	} else {
+		gm, err = game.NewGame(file)
+		if err != nil {
+			msg = err.Error()
+		} else {
+			box, err := boxscore.NewBoxScore(gm, ui.RE)
+			if err != nil {
+				msg = err.Error()
+			} else if box.HomeLineup.TeamStats != nil && box.VisitorLineup.TeamStats != nil {
+				scoreTable := box.InningScoreTable()
+				scoreTable.Columns[0].Name = ""
+				rc := box.AltPlays().GetColumn("RCost").GetSummary()
+				boxScore = fmt.Sprintf("%s\nMisplay runs = %.2f", scoreTable, rc)
+			}
+		}
+	}
+	ui.Logger.Println("updating message: ", msg)
+	ui.Logger.Println("update took ", time.Since(t0))
+	ui.app.QueueUpdateDraw(func() {
+		ui.messages.SetText(msg)
+		if boxScore != "" {
+			ui.box.SetText(boxScore)
+		}
+		if gm != nil {
+			ui.homePlays.SetTitle(gm.Home.Name)
+			ui.visitorPlays.SetTitle(gm.Visitor.Name)
+		}
+		ui.properties.ClearColors()
+		ui.homePlays.ClearColors()
+		ui.visitorPlays.ClearColors()
+		for _, err := range allErrors(err) {
+			if gerr, ok := err.(interface{ Position() gamefile.Position }); ok {
+				line := gerr.Position().Line - 1
+				switch {
+				case line < ui.visitorPlaysStart:
+					ui.Logger.Println("highlighting properties line ", line)
+					ui.properties.LineColors[line] = &errorColor
+				case line < ui.homePlaysStart:
+					ui.Logger.Println("highlighting visitor plays line ", line-ui.visitorPlaysStart)
+					ui.visitorPlays.LineColors[line-ui.visitorPlaysStart] = &errorColor
+				default:
+					ui.Logger.Println("highlighting home plays line ", line-ui.homePlaysStart)
+					ui.homePlays.LineColors[line-ui.homePlaysStart] = &errorColor
+				}
+			}
+		}
+	})
+}
+
+func allErrors(err error) []error {
+	if err == nil {
+		return nil
+	}
+	if m, ok := err.(*multierror.Error); ok && m.Len() > 0 {
+		return m.Errors
+	}
+	return []error{err}
+}
+
+func (ui *UI) getGameText() string {
+	var buf bytes.Buffer
+	fmt.Fprint(&buf, ui.properties.GetText())
+	if buf.Len() > 0 && buf.Bytes()[buf.Len()-1] != '\n' {
+		fmt.Fprintln(&buf)
+	}
+	fmt.Fprintln(&buf, "---")
+	fmt.Fprintln(&buf, "visitorplays")
+	ui.visitorPlaysStart = lineCount(buf.String())
+	visitorPlaysText := ui.visitorPlays.GetText()
+	fmt.Fprint(&buf, visitorPlaysText)
+	ui.homePlaysStart = ui.visitorPlaysStart + 1 + lineCount(visitorPlaysText)
+	if buf.Bytes()[buf.Len()-1] != '\n' {
+		fmt.Fprintln(&buf)
+		ui.homePlaysStart++
+	}
+	fmt.Fprintln(&buf, "homeplays")
+	fmt.Fprintln(&buf, ui.homePlays.GetText())
+	ui.lastUpdate = time.Now()
+	ui.Logger.Println("got game text at ", ui.lastUpdate)
+	return buf.String()
+}
+
+func lineCount(s string) (count int) {
+	for _, ch := range s {
+		if ch == '\n' {
+			count++
+		}
+	}
+	return count
+}
+
+func (ui *UI) parseGame(gamePath string) {
+	ui.path = gamePath
+	ui.status.SetText(path.Base(ui.path))
+	ui.box.SetText("")
+	ui.messages.SetText("")
+	ui.properties.SetText("", false)
+	ui.homePlays.SetText("", false)
+	ui.visitorPlays.SetText("", false)
+	f, err := os.Open(ui.path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return
+		}
+		ui.messages.SetText(fmt.Sprintf("cannot parse %s: %s", ui.path, err))
+		return
+	}
+	defer f.Close()
+	scanner := bufio.NewScanner(f)
+	state := "props"
+	var (
+		buf         strings.Builder
+		targetPlays *LinedTextArea
+	)
+	for scanner.Scan() {
+		line := scanner.Text()
+		switch {
+		case state == "props":
+			if line == "---" {
+				state = "plays"
+				ui.properties.SetText(buf.String(), false)
+				buf.Reset()
+			} else {
+				fmt.Fprintln(&buf, line)
+			}
+		case state == "plays" && line == "homeplays":
+			state = "homeplays"
+			targetPlays = ui.homePlays
+		case state == "plays" && line == "visitorplays":
+			state = "visitorplays"
+			targetPlays = ui.visitorPlays
+		case targetPlays != nil:
+			if (line == "homeplays" || line == "visitorplays") && line != state {
+				targetPlays.SetText(buf.String(), false)
+				buf.Reset()
+				if state == "homeplays" {
+					targetPlays = ui.visitorPlays
+					state = "visitorplays"
+				} else {
+					targetPlays = ui.homePlays
+					state = "homeplays"
+				}
+			} else {
+				fmt.Fprintln(&buf, line)
+			}
+		}
+	}
+	if targetPlays != nil {
+		targetPlays.SetText(buf.String(), false)
+	}
+	ui.lastKey = time.Now()
+}
+
+func (ui *UI) inputHandler(event *tcell.EventKey) *tcell.EventKey {
+	var focusInc int
+	switch event.Key() {
+	case tcell.KeyCtrlQ:
+		ui.app.Stop()
+	case tcell.KeyCtrlC:
+		return nil
+	case tcell.KeyCtrlS:
+		if ui.dialog == nil {
+			ui.save()
+		}
+		return nil
+	case tcell.KeyCtrlL:
+		if ui.dialog == nil {
+			ui.showDialog(NewChooser(path.Dir(ui.path), ui.path, func(s string, newgame bool) {
+				ui.closeDialog()
+				if s != "" {
+					if newgame {
+						ui.newGame(s)
+					} else {
+						ui.parseGame(s)
+					}
+				}
+			}))
+		}
+		return nil
+	case tcell.KeyCtrlP:
+		return tcell.NewEventKey(tcell.KeyUp, 0, 0)
+	case tcell.KeyCtrlN:
+		return tcell.NewEventKey(tcell.KeyDown, 0, 0)
+	case tcell.KeyCtrlF:
+		return tcell.NewEventKey(tcell.KeyRight, 0, 0)
+	case tcell.KeyCtrlB:
+		return tcell.NewEventKey(tcell.KeyLeft, 0, 0)
+	case tcell.KeyUp:
+	case tcell.KeyDown:
+	case tcell.KeyLeft:
+	case tcell.KeyRight:
+		break
+	case tcell.KeyTAB:
+		focusInc = 1
+	case tcell.KeyBacktab:
+		focusInc = -1
+	default:
+		switch {
+		case ui.properties.HasFocus():
+			fallthrough
+		case ui.homePlays.HasFocus():
+			fallthrough
+		case ui.visitorPlays.HasFocus():
+			if !ui.modified {
+				ui.modified = true
+				ui.status.SetText(ui.status.GetText(false) + "*")
+			}
+			ui.lastKey = event.When()
+			ui.Logger.Println("got key at ", ui.lastKey)
+		}
+	}
+	if focusInc != 0 {
+		f := ui.app.GetFocus()
+		j := 0
+		for i := range ui.focusOrder {
+			if ui.focusOrder[i] == f {
+				j = i + focusInc
+				if j < 0 {
+					j = len(ui.focusOrder) - 1
+				} else if j == len(ui.focusOrder) {
+					j = 0
+				}
+			}
+		}
+		ui.app.SetFocus(ui.focusOrder[j])
+		return nil
+	}
+	return event
+}
+
+func (ui *UI) newGame(gamePath string) {
+	file, _ := gamefile.ParseFile(gamePath)
+	if file != nil {
+		newFile, _ := file.WriteNewGame(false)
+		if newFile != nil {
+			ui.parseGame(newFile.Path)
+			return
+		}
+	}
+	m := regexp.MustCompile(`(^.*-)([0-9]+)\.gm$`).FindStringSubmatch(gamePath)
+	var newGamePath string
+	if m != nil {
+		n, _ := strconv.Atoi(m[2])
+		if n != 0 {
+			newGamePath = m[1] + fmt.Sprintf("%d", n+1) + ".gm"
+		}
+	}
+	if newGamePath == "" {
+		newGamePath = path.Join(path.Dir(gamePath), time.Now().Format(gamefile.GameDateFormat)+"-1.gm")
+	}
+	ui.parseGame(newGamePath)
+}
+
+func (ui *UI) save() {
+	text := ui.getGameText()
+	var canonName string
+	gf, _ := gamefile.ParseString(ui.path, text)
+	if gf != nil {
+		gm, _ := game.NewGame(gf)
+		if gm != nil && gm.GetDate().Unix() != 0 && gm.Number != "" {
+			canonName = fmt.Sprintf("%s-%s.gm", gm.GetDate().Format("20060102"), gm.Number)
+			if canonName == path.Base(ui.path) {
+				canonName = ""
+			}
+		}
+	}
+	doSave := func() {
+		originalPath := ui.path
+		if canonName != "" {
+			ui.path = path.Join(path.Dir(ui.path), canonName)
+		}
+		f, err := os.Create(ui.path)
+		var msg string
+		if err != nil {
+			msg = fmt.Sprintf("[yellow:red]%s", err.Error())
+		} else {
+			_, _ = f.WriteString(text)
+			f.Close()
+			msg = fmt.Sprintf("%s [green]saved", ui.path)
+		}
+		ui.messages.SetText(msg)
+		ui.modified = false
+		ui.status.SetText(path.Base(ui.path))
+		if canonName != "" {
+			_ = os.Remove(originalPath)
+		}
+	}
+	if canonName != "" {
+		ui.showQuestionDialog(fmt.Sprintf("Rename %s to %s ?", path.Base(ui.path), canonName), "OK", doSave)
+	} else {
+		doSave()
+	}
+}
+
+func (ui *UI) showDialog(dialog tview.Primitive) {
+	if ui.dialog == nil {
+		ui.dialog = dialog
+		ui.root.AddPage("dialog", dialog, true, true)
+		ui.app.SetFocus(dialog)
+	}
+}
+
+func (ui *UI) closeDialog() {
+	ui.root.RemovePage("dialog")
+	ui.dialog = nil
+}
+
+func (ui *UI) showQuestionDialog(question string, okLabel string, ok func()) {
+	modal := tview.NewModal().AddButtons([]string{okLabel, "Cancel"}).
+		SetText(question).
+		SetDoneFunc(func(buttonIndex int, buttonLabel string) {
+			if buttonLabel == okLabel {
+				ok()
+			}
+			ui.closeDialog()
+		})
+	ui.showDialog(modal)
+}
+
+func (ui *UI) backgroundUpdate(ticker *time.Ticker, done <-chan bool) {
+	for {
+		select {
+		case <-ticker.C:
+			ui.app.QueueUpdate(func() {
+				if ui.lastKey.After(ui.lastUpdate) {
+					go ui.update()
+				}
+			})
+		case <-done:
+			return
+		}
+	}
+}
+
+func (ui *UI) Run(path string) error {
+	ticker := time.NewTicker(250 * time.Millisecond)
+	done := make(chan bool)
+	go ui.backgroundUpdate(ticker, done)
+	if path == "" {
+		path = "."
+	}
+	fi, err := os.Stat(path)
+	if err != nil {
+		return err
+	}
+	if fi.IsDir() {
+		ui.showDialog(NewChooser(path, "", func(s string, newgame bool) {
+			if s == "" {
+				ui.app.Stop()
+			} else {
+				ui.closeDialog()
+				if newgame {
+					ui.newGame(s)
+				} else {
+					ui.parseGame(s)
+				}
+			}
+		}))
+	} else {
+		ui.parseGame(path)
+	}
+	err = ui.app.Run()
+	ticker.Stop()
+	done <- true
+	return err
+}