Another for the 3D crowd, https://birdmaskstudio.itch.io/zombie-gaggle
3D is all I know, and I keep my games low poly so I can manage to get a good amount of assets even within Jam deadlines. I think most people do 2D on Jams because when you have to make everything for the Jam(which is usually the case), you can do a lot of visuals in a short amount of time if you know how to work with 2D stuff. Now to sell my game;
A quick-to-play, 5 level zombie puzzle game. You steer a crowd of survivors and must get at least one of them across the road and past the zombie horde. Any ratings and comments would be appreciated!