Base games for use in a game jam for Unity

We'll be doing a game jam tomorrow, and I'd like to see if there were any good base resources that people use / should use for game jams, on a $0 budget.

I'd rather spend as little time as possible reinventing wheels, so if we're making a platformer, I'd rather tweak an existing system than potentially waste time on something stupid before I even get to the innovative part of the game.

We're definitely using 2D, and avoiding multiplayer. Platformer is the main one since getting it to feel good in unity is always difficult, but other genres like roguelike or RTS would be nice to have on hand.