Campaign

Fifty crossings, in six bands that each introduce one idea and then play with it: slow one-way lanes, then both directions at once, then faster traffic, then fewer places to stand, then dense bands, and a finale with one fewer life.

Every crossing is proved completable without losing a life before it ships. Because the traffic moves, the check searches position and timing together — it knows the board repeats, so it can prove a route exists rather than sample for one.