Without a token the app uses the evaluation token built into CesiumJS, which Cesium may rate-limit or rotate; if it stops working the app falls back to MapLibre on its own. A free ion account token lifts that. Keys stay in this browser only (local storage) and are never uploaded.
Keys: W A S D move, Q E down/up, arrows look, Shift faster, Space pause, 1-5 paths, H hide UI, R surprise.