I think it is best to go for a game that can be played on the web for the jams, because it is really hard to get people to download your game but rather easy to get them play it on the web without an download. But if you are going for a desktop-only, I personally would try to keep it smaller than 100mb. The bigger the game, the bigger the peoples expectations generally are when the game is downloading. Also thank you for taking time answering too, best of luck!