After a few hours of floundering (ha!), I've finally come up with my idea.

So to a fish living in a fishbowl, the bowl is their whole world, right? What happens when the fish leaves the fishbowl?? What happens when the fish leaves the fishbowl via jetpack??

So that's my game. Fish gets a jetpack and leaves their tiny fishbowl to try to escape to the ocean.