Rotate cam lobes to phase-align every valve at the target crank angle. Timing belts couple cams — idler gears break the chain. A mechanical puzzle of pure phase logic.
Goal: At the target crank angle (gold marker), every valve must be OPEN (lobe pointing up).
Rotate: Tap a sub-chain's ◀ ▶ to phase-shift all its cams together (timing-belt coupling). Idlers: A gear icon between cams splits them into independent sub-chains — each rotates separately. Win: All valves aligned at the gold angle. Fewer moves = more stars.