Tap an outlined spot to explore, or hold it to rescue a crab. You can expand beside any explored spot, including diagonally.

Tap the flag icon, then tap covered spots to mark or clear possible crabs. Tap the icon again to explore. Flags are just notes. Hold a flagged spot when you’re ready to rescue it.

A number counts crabs still hiding in its eight neighbours. Each colour starts with one crab. Rescue it to clear that whole colour.

Rescue everyone, then tap the exit hole. A wrong tap or hold costs a heart. The lightbulb explains a certain next move.

The level grid saves the most hearts you’ve finished with. Replay a level to improve your best.