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Race keys: left and right steer, up and down change gear, Enter accelerates, Insert brakes (the CONTROL screen redefines them, and takes a game pad or the mouse). P pauses, Esc leaves. Player 2's keys are not set until you define them: CONTROL, then DEFINE KEYS (the game's own screen). Any key works there, WASD included.
Your settings and best scores are kept in this browser. Alt+Enter: full screen. Ctrl+F11: 4:3 or square pixels. Ctrl+F12: sharp or whole-number scaling. Ctrl+F9: the next screen filter.
Only in full screen can the game have the whole keyboard, desktop shortcuts like Alt+Space included, and only in Chrome, Edge and other Chromium-based browsers (hold Esc to leave full screen). In a window, or in Firefox, the desktop and the browser keep their shortcuts.