Layer 2 Blockchains for Videogames

As of July 2023, blockchains are becoming increasingly popular, and they are starting to be used in many different fields.

Videogaming is one such field.

In this report it will be explored:

• How a blockchain can be used in the world of videogames
• Why more scalable layer 2 blockchains are needed
• What are rollups and why they are particularly well suited for videogames
• What is Starknet and how to deploy a smart contract on it
• A simple implementation of a Starknet smart contract to open loot boxes in a completely transparent way (and a demo client to use this smart contract)

Table of contents

Part I - Blockchain concepts and their limitations

• What is a blockchain 5
  • Transactions
  • Miners
  • Proof of work
  • Journey of a transaction
  • Blockchain programmability
  • Tokens
• Why blockchain can be used in videogames
• Why blockchain cannot be used in videogames

Part II - Blockchain: layer 2

• Off-chain state channels 12
  • State channels and videogames
• Sidechains
• Rollups
  • Optimistic rollups
    • Entering an optimistic rollup
    • Exiting an optimistic rollup
    • L2 - L1 interaction
    • Optimistic rollups and videogames
  • Zero-knowledge rollups
    • Entering a ZK rollup
    • Exiting a ZK rollup
    • L2 - L1 interaction
    • Intuition on the validity proofs
    • ZK rollups and videogames

Part III - Starknet

• Account abstraction
• Starknet actors
  • Sequencers
  • Provers
  • Nodes
• Transaction journey
• Starknet setup
  • Prerequisites
  • Install Python3.9
  • Install Cairo and Starknet
  • Setting up environment variables
  • Creating an account
  • Deploying and interacting with a smart contract
• Cairo
  • General concepts
  • Storage
  • Contract sections

Part - IV - Implementation: immutable loot boxes

• Problem statement
• The smart contract
• The client

Part V - Appendix

• Merkle trees
  • Merkle proof