The Data.rsdk file is a "datapack" used by the Retro Engine (RSDK), which powers Sonic Mania . Because the fan-developed Android ports are only the "engine" code (the brain), they need this datapack (the body) to actually display the game. How to Legally Obtain Data.rsdk
Think of it like this: Owning a Blu-ray of a movie allows you to rip a digital copy for personal use. It does not allow you to share that rip with the world. Same goes for Data.rsdk . sonic mania data.rsdk download android