Skeeball
Several alleys, physical targets, a limited supply of balls. Your marble was already the right shape for this.
The alley is real geometry and the targets are real objects — the marble rolls up the lane and into them under the same solver that carries it down a mountain. Nothing about the physics is swapped out.
What changes is everything around it: the camera, the scoring, the shape of the level, and the loop. You get a limited number of balls, the lane resets itself between throws, and the arcade around you is set dressing you cannot touch.
It is the first release candidate for a reason. It proves a mode can take over the framing without taking over the marble.