How to Play
- Select: Tap/click a cell or use Arrow keys. Home/End jump to row start/end.
- Enter digit: Tap a pad button or press 1–9.
- Erase: Backspace, Delete, or 0.
- Notes mode: N toggles mode; Shift+1–9 toggles a single note without switching modes.
- Undo: Ctrl/Cmd+Z (last 20 actions).
- Pause: P or Esc.
- Mute: M.