Connect Four

Drop your discs into a seven-column grid and be the first to line up four in a row — horizontally, vertically or diagonally. It takes seconds to learn and much longer to master.

Game Oix's opponent uses an alpha-beta search with a positional evaluation. It looks two moves ahead on Easy (and sometimes plays randomly), four on Medium, six on Hard and eight on Expert. You always move first, which in theory gives you the advantage.

1. Click or tap a column to drop your cyan disc to the lowest free space.
2. The computer then drops a pink disc.
3. Connect four of your discs in a line to win. If the board fills up, the game is a draw.

• Take the centre column early.
• Check for immediate threats every move — especially diagonals.
• Never fill the space under an opponent's winning square.
• Build double threats, including stacked threats in one column.
• Use odd and even rows in the endgame: the first player benefits from threats on odd rows.

Guide: Connect Four Strategies and Common Mistakes.