1. Start at checkpoint 1 and drag (or click cell‑by‑cell) through adjacent tiles.
2. Reach checkpoints 2, 3, 4… in order — you can't skip ahead to a later one.
3. Cover every tile on the grid exactly once with a single unbroken route.
4. The route doesn't have to end on the last checkpoint — once it's reached, keep filling whatever tiles remain, in any order, and finish wherever the route naturally runs out.
5. Retrace back over your route one tile at a time to undo, or use Undo. Clear wipes the current attempt and starts the same course over from scratch.

On Hard and Expert courses, thick ink bars mark ridgelines your route can't cross.

Your score starts from a difficulty base and loses points for time, backtracks, and any extra moves beyond the grid's tile count — the clock itself stops the moment you hit the last checkpoint, so tidying up the rest of the grid costs no time.

Solve reveals a valid route from wherever you currently are — handy when you're stuck, but a revealed course isn't recorded in your stats.

Every course gets a 6-digit code. Share it with a friend and they get one attempt at your exact course — loading a code you've already played shows the leaderboard instead of a fresh board.