Tip: add this page to your home screen for a full-screen app. On iPhone and iPad: Share → Add to Home Screen. On Android: menu → Add to Home screen or Install app.
Keyboard: Enter sends, ↑/↓ recall earlier commands, Esc clears. Numpad moves (8 north, 2 south, 4 west, 6 east, 9/3 up/down).