Complete three tests: stop the clock on its target, tap twice as quickly as possible, and estimate the sound interval. Each test is worth up to 1,000 points. Your total out of 3,000 is submitted at the end.

Fly with the stick (or WASD/arrows) - your cannon fires by itself. Grab orange capsules: each one moves the selector at the bottom. Press ACTIVATE (or K) to cash the chain in for that hardware. Repeated buys raise the tier. Bosses end each level. Don't touch anything that glows red.

Hold the LEFT or RIGHT side of the screen to steer your sinking probe. Sonar pings reveal the walls for a moment - remember them. Jellyfish glow on their own and give bonus score plus a free light burst. Mines barely glow at all. Survive as deep as you can.

WASD or arrow keys to fly. Hold Space to fire. B or Enter drops a bomb. F releases flares and is the sure answer to a missile lock. Shift or E triggers overdrive. P or Escape pauses, and Q stands down. On touch, drag to fly and use the on-screen buttons. Skim close to enemy fire to charge overdrive. Destroy ground targets for upgrades. Only finishing all five stages posts a score to the leaderboard.