Connect Four: Why the Center Column Wins

Connect Four looks like a simple children's game, but under the surface it is a game with a provably correct strategy. In 1988, James D. Allen and Victor Allis independently published full solutions showing that the first player, playing perfectly, always wins from the standard 7-column, 6-row starting position. The key move: drop your first disc in the center column.

The 13-line rule

Every cell on the Connect Four board participates in a certain number of potential four-in-a-row lines. Count horizontals, verticals, and diagonals through each cell. Edges and corners participate in only 3 to 5 lines each. The center column cells participate in 7 to 13 lines, with the very center square touching the most.

The first-player advantage

Allis's 1988 proof demonstrated that with optimal play starting with a center opening, the first player wins by move 41 of a 42-move game. That is a tight margin, which is why casual players rarely notice the advantage. A single suboptimal move by the first player usually hands the game to the second player.

If you go first, always play the center column. If you go second and your opponent plays center, stack on top. If they play anywhere else, take center yourself — you have been handed a significant advantage.

Traps worth knowing

• The 7-trap. Build a 3-in-a-row on the second row with open spaces on both ends. The opponent can only block one.
• The double threat. Arrange two separate winning threats on the same turn. The endgame-winning combination in most competitive games.

Try the Connect Four game. Our CPU uses a reasonable heuristic, not perfect play, so center-column openings give you a real edge.