Connect Four

About this test

Connect Four is a line-up game with gravity: seven columns, six rows, and discs that always fall to the lowest free cell. That constraint changes the game entirely compared with tic-tac-toe, because you don't choose where your disc lands, only which column it goes down.

The game was solved mathematically in 1988, independently by Victor Allis and by James Dow Allen: the first player, playing perfectly and opening in the centre column, always wins. Any other opening throws that advantage away, and opening on an edge column actually loses against perfect play. That makes Connect Four one of the few classic board games whose exact outcome is known.

In practice, three ideas are enough to beat most opponents. First, take the centre, which participates in the most possible lines. Second, build a double threat: two open lines of three in different places, impossible to block with one disc. Third, watch the cell directly above the one you're filling, because filling yours hands that cell to your opponent — the gift move, and the cause of half of all losses.

How it works

Three rounds, you always move first. Only wins count; a draw, very rare on a forty-two-cell board, is worth nothing. The 0-100 score runs from zero to three wins.