Place a stone to trap a line of your opponent's stones: they flip to your color. Most stones at the end wins.
You play the dark stones and always move first.
Corners can never be flipped back, so they're the best squares. Avoid the squares right next to an empty corner: they hand the corner to your opponent. Early on, fewer stones and more choices beats grabbing lots of stones.
Hint suggests a move. Take back undoes your last move once per game.