I noticed that one of the challenges was to do with gamemaker and the instructions said about collision and camera code. Does this mean that the jam is gamemaker only?

Hello, seems like its just optional to be gamemaker engine, probably that will grants you a better score, but not sure :3

Hello! It does not need to be in GameMaker Studio. Doing so is an optional challenge for yourself and will not be a graded/voted metric. :D

Great, thanks! I think I'll be working in unreal for this jam, as I want to get better accustomed with the engine.