Mad Fish

The fish swims forward on its own and the only input is up or down. That sounds trivial until buoyancy gets involved: releasing the control does not stop the fish, it merely lets it drift on a little further, which is behind nearly every collision.

The correction is starting the movement roughly a body-length before the obstacle rather than when it arrives. Anyone with experience of this family adjusts quickly, while players used to games that stop dead the moment input ends will find this fish oddly stubborn for the first few attempts.

The scenery narrows as the distance grows, from comfortable openings down to gaps that need constant small corrections. That progression is what makes long runs more interesting than short ones — everything practised at the start gets called on at once near the end.