I would be curious about your favorite coop games. I often find them a big lacking, often being a bit unbalanced. An example is Battle for Hogwarts, where one game can be a walk in the park and another absolutely impossible and rarely is there a balanced match.
Roll camera is Co-op and really fun. The theme is that you are making a movie. During the game you have to balance budget and time while trying to shoot all the scenes of the movie, and while problems are continuously happening. It may be balanced to the easy side generally, but you can tweak the difficulty by starting with different budgets and amounts of time.