Minesweeper

Reveal squares: Left-click or tap. If it's a mine, you lose!
Use the numbers: A number tells you exactly how many mines are touching that square (including corners).
Safe starting: Your very first click is guaranteed to be safe.

Corners first: Clicking near edges often opens large blank spaces.

Chording (Speed move): If a number is touching the correct amount of flags, click the number itself to instantly open the remaining squares around it.

Don't guess: Use the "Training" difficulty to learn the logic using the Hint button.