Hex-grid reef defense. Ocean currents shift which lanes are open every 20 seconds, dragging plankton-swarm enemies along new paths. Anemone, urchin and crab towers each suit different current directions. Signature: read the current arrows and pre-position before the shift.
Bioluminescent teal and violet reef, drifting light rays, pulsing polyps, bubble particles.
Click, Enter or Space to start. Place and upgrade towers with the mouse and number keys, or by tapping on touch, to stop each enemy wave before it reaches your goal. The HUD tracks lives, cash and wave.