I haven't tried this as yet, but I have read the comments so far. Ideally this game jam is about creating games, and again ideally with a Windows execution file so they can be played as a standalone. The use of a third party application, especially one that requires someone to sign up isn't really an expectation of players to commit to, and shouldn't be either for a game jam. I think what we have here is a 'mod' for an already established game. I am familiar with Roblox so I will indeed check it out, but I wouldn't expect others to do so I'm afraid.