Hello, Robbie, thanks for joining! The scope of #RPGenesis is for each participant to create a new RPG by writing at least five thousand words within a week. We're not making content for already existing games.
Welcome Alamantus! You can also do an hack of an existing game. What about a simplified version of GUTS+ System? It could be GUTS+ Accelerated or GUTS+ Fast, or maybe a more compext version of it! You can work on top of what you already have <3 Good luck !