Eh, I'm kinda against the sentiment of making a genre-based theme. I'd feel that'd do a lot to make all the games feel "same-y". Like, if all the games are platformers, there's only so much you can really do, and to be quite honest, most games would end up being not-Mario. Likewise, for racing games, fighting games, etc. there's also games that many people will try to emulate. Personally, I'd rather see more variety in the jam, especially since the CGA aesthetic is criminally underused by indies. It would kinda stink to see so many people make what amounts to essentially the same game with a new coat of paint.