Race marbles down four tracks between the same two points and watch the steepest ramp lose. Shape your own track, let a search rediscover the curve of fastest descent, and see why a marble released anywhere on it arrives at the same instant. Entirely client-side: no model, no credits, no network. An independent reimplementation; a marble run is a generic toy with no single author, and the physics is credited to Huygens (1659), Bernoulli (1696) and Newton (1697).

Every public app is built from a security-scanned skill and must pass a clean scan — skill and frontend — before it can be listed. Have a skill of your own? Turn it into an app — or read the step-by-step walkthrough.