Hey! We are open to any and all games, including tabletop and card games. If Roblox is what you want to build your game in, I say go for it! It certainly will be accepted for the jam. If it requires Roblox to be installed to play, it might not be played on stream (I'm unfamiliar with the system), but this game jam is all about setting aside time to build a game. So long as you learn something new from it, that's all that's really important.
SecretJuice1 has the right of it. People have different skills, preferences, and are at different stages of the process. This jam is meant for everyone, regardless of engine preference or coding skill. This jam is not judged or ranked outside of the Core category and that is being handled by Core Games, not Extra Credits.
We want to encourage everyone to keep an open mind. Someone compared Roblox to Lego, but there have been some incredible works of artistry with Lego. Please design you feel fits the scope & aim of your project best. Thank you.