A game where you’re all firefighters (or rather firetrucks) in a randomly generated city that’s on fire far too often.
On its own, this idea already works. You have a clear and intuitive goal everyone understands: drive towards fires and hose them until extinguished. It’s already a nice challenge for cooperation and optimization.
But when prototyping I found something that’s even better: each truck is essentially a firehose attached to the fire station/your starting point. As you drive around, that hose will wrap around buildings and stuff, like rope or elastic. The hose is just a simple rope physics simulation, with very thick cylinders to make it easily visible.
Now you have an extra challenge: you have to move around within the constraints of that firehose!
I don’t know why I stopped developing that prototype. It was quite promising. But this is an old idea of mine, so the reason for abandoning it is usually “too busy with school”.