Tumbleglass

Tumbleglass runs a fixed-step deterministic solver so a run can be replayed from a seed in a few kilobytes. That makes leaderboards verifiable: we re-simulate submitted runs server-side and reject anything that diverges.

It is also where we learned to be ruthless about frame time. The first build dropped frames on anything below a Snapdragon 7-series once forty marbles were in flight. Rewriting broad-phase collision onto a spatial hash and capping active marbles per chamber brought median frame time to 19 ms across our test rack of eleven real handsets.

Those eleven devices are still on a shelf in the studio, and nothing ships without running on all of them.