The object: find the mines quickly without setting them off.

• Left-click a square to open it. The number shows how many mines touch it.
• Right-click marks a square with a flag, then a question mark, then clears it.
• Middle-click or double-click an open number to open its neighbours when enough flags are set.
• If you open a mine, the game is over. Flag all mines to win.
• Smiley face (or F2) starts a new game.

Minesweeper — a Windows 3.11-style clone.

Beginner: 9×9 · 10 mines
Intermediate: 16×16 · 40 mines
Expert: 30×16 · 99 mines