Sunbringer is the asset bundle for Stormsinger, and is named for the angel who holds the sun upon his charred back. It contains all of the assets used in the game, including textures, models, and sounds. When the game launches for the first time, the Sunbringer folder is compressed into a binary format to be used during actual execution, and the folder is deleted. This also compiles the included shaders into bytecode. None of the content in this folder remains in a recognizable state after the first run of the game.
The binary format of the Sunbringer asset bundle attempts to be as intuitive as possible without sacrificing any compression. I always seek to improve its algorithm, and if you have any suggestions please open an Issue.
The specification of the format is still being worked on. For now, take a gander at the code and produced binary to see where everything goes.