Floppy Fish
Floppy Fish uses gravity as its main mechanic and the objective is to survive as long as possible while collecting treasures to get higher scores, and i find the simple controls helpful.
How To Play Floppy Fish
You tap to move the fish upward, and release to let it descend, avoiding obstacles and collecting treasures.
Controls and Features
The only stated control is tapping or clicking to make the fish swim upwards, and no extra buttons or toggles are stated.
Tips
Practice timing your taps to descend and ascend effectively, and you must dodge obstacles and collect treasures whenever you see them.
Similar Gravity Fish Arcade Game
Survive by tapping to ascend and releasing to descend, collecting treasures for higher scores, and I think the simple controls are helpful, while playing Floppy Bird with the same physics and obstacles as this one.