You mean assets... off the shelf? Sorry, couldn't resist. Anyway, on overview page it says that
Using pre-made assets is no problem, just make sure that you have the necessary rights to use them, and attribute them in your game’s description properly
I've also used template project with aforementioned functionality in past jams. I think generic template project it fits the description. IMHO 3 hours is better used developing the game itself. As a disclaimer this is just my take on rules, I'm not associated with jam hosts.