Your Piece is a ramp handle
Tap a ramp, then slide or twist your Piece.
Place one conductive Arcade Piece on the circle, facing →. Let go to check it.
Why did it roll?
A downhill ramp trades height for speed. A curved trough redirects the marble. Try changing one ramp and see what changes!
The game uses real 3D sphere contacts, gravity, friction and a faceted open channel in Rapier. Editing handles are aids. Game materials are simplified; this is not a material or engineering safety test. Native USD B-rep is not integrated.
Desktop keys: 1–3 choose a ramp; arrow keys move it; A/D tilt it; Space drops a marble.