Connect Four

Connect Four went on sale from Milton Bradley in 1974, though the drop-a-disc idea is older — folklore attaches a version called The Captain's Mistress to Captain Cook's voyages. The format has not changed since: a vertical 7×6 grid, gravity pulls each disc to the lowest free slot in its column, and the first player to line up four in a row — horizontally, vertically or diagonally — wins.

It is also one of the most famous solved games. In 1988 James Dow Allen and Victor Allis independently proved that with perfect play the first player wins, but only by opening in the centre column; start anywhere else and a perfect opponent can hold a draw or better. In practice nobody navigates the game's four-and-a-half trillion positions perfectly, so the human fundamentals still decide matches: control the centre, build two threats at once so only one can be blocked, and mind parity — the first player generally wants a winning square on an odd row counting from the bottom, the second player on an even row.

Here you can pass-and-play a friend on one screen or face a genuine minimax engine at four strengths, from an Easy setting that deliberately blunders to an Expert that searches eight plies ahead and never gives a game away. Choose who moves first, take back moves, ask for a hint when stuck, and let the scoreboard keep a running series across rounds.