Your finger becomes a road. Draw a line and the little ball rolls along it, obedient for once, toward the goal. Each finished path is a point. Clip an obstacle and you lose a life — three of them, gone faster than you expect once the trails start twisting. There's a strange satisfaction in tracing a clean arc that takes the ball exactly where you meant it to go, and a small betrayal when a curve you drew too lazily sends it into a spike. Slow hands lose. Careful hands get a slightly better score. Then the board gets meaner anyway.
Your finger becomes a road.