About Connect Four
Connect Four is a classic strategy game for two. Drop discs into the seven columns and be the first to line up four in a row, column or diagonal. Each disc falls to the lowest free space, so every move changes the shape of the board.
Warm up against the easy AI, test your strategy against the hard AI that searches several moves ahead, or play a friend on the same screen.
How to play
- Click or tap a column to drop your pink disc.
- Line up four discs of your color to win the round.
- Control the center column. It is part of the most possible lines.
Connect Four rules
Connect Four is played on a vertical board of seven columns and six rows. Players take turns dropping a disc into a column, and the disc falls to the lowest empty space. The first player to line up four discs in a row, horizontally, vertically or diagonally, wins. If the board fills with no line of four, the game is a draw.
Connect Four is a solved game: in 1988 James D. Allen and Victor Allis showed independently that the first player can always win with perfect play by starting in the centre column.
Strategy that actually wins
- Own the centre column. A disc in the middle can be part of more possible fours than a disc on the edge.
- Look for double threats. Like a fork in tic-tac-toe, two open threats at once usually win the game.
- Do not set up your opponent. Before dropping a disc, check whether it gives them a space to play right above it.
- Use odd and even rows. Counting rows from the bottom, the first player benefits from threats on odd rows (1, 3, 5) and the second player from threats on even rows (2, 4, 6). Late in the game these threats decide who is forced to fill the critical square.
- Block vertical threes immediately, but think twice before blocking a horizontal two; it may be a trap.
Modes
Easy AI is a relaxed opponent for quick games. Hard AI looks six moves ahead, so plan your threats carefully. 2 Players puts pink against yellow on one device.
Connect Four FAQ
Who goes first?
You play the pink discs and move first against the computer.
Can you win if you go second?
Against perfect play, no. Against a human, or a computer that makes a slip, yes: play solid defence and build even-row threats.
More two-player classics: Tic-Tac-Toe, Reversi and Checkers.
