The rules are:

You can only use assets and code that are legally yours or are free to use. 

The game must be after the jam has started.

You can join in teams if you want or be solo.

You cannot submit someone else's game.

You can upload while the voting is happening if the game hasn't fully been finished but you must leave the original version.

And don't forget to have fun.

That's all, thanks.

Message on the jam community board if you have any questions.