Drag anywhere (or move the mouse, or ← → / A D) to slide your bathysphere. It fires all the time, 2 darts in the water at most, so line up your shots.
Jellies of one colour that touch are threaded together. A jelly that dives keeps a thread back to its group.
Hit a diver below the glow line and a pulse bursts its whole group, paying more for every jelly. In the middle it takes one neighbour with it; up high it bursts alone. Rings show what a hit would set off.
Jellies in the swarm have a shell: the first hit cracks it. Divers burst in one hit (Queens take 2).
A diver or a red sting dart costs a life (3). If the swarm sinks to the glow line, everything dives.
Waves roll straight on, each one harder, up to wave 99. New kinds of jelly join as you go. Every 10 waves cleared earns a life (up to 5).