How to play
The board stands upright with 7 columns and 6 rows. Players take turns dropping one disc into a column, and it falls to the lowest empty space. Red moves first. The first to line up four of their discs across, down or diagonally wins. If all 42 spaces fill up with no line of four, the game is a draw.
Strategy tips
- Take the middle: the center column is part of more possible lines of four than any other column.
- Check the space above: before you drop a disc, look at the space directly above it. If that space would complete your opponent's four, your move hands them the win.
- Build threats that cannot be blocked yet: a winning space that floats above empty spaces cannot be filled by your opponent, and sooner or later someone has to play underneath it.
- Make two threats: two winning spaces, especially one stacked on the other, usually decide the game.
A solved game
The standard 7×6 game was solved in 1988, first by James D. Allen and about two weeks later, independently, by Victor Allis. With perfect play the first player wins, but only by starting in the middle column. The hard level here reads several moves ahead with alpha-beta search but is not perfect, so careful play can beat it.