Connect Four (also known as Plot Four, Find Four, Four in a Row, and Four in a Line) is a two-player game in which the players first choose a color and then take turns dropping their colored discs — known as "checkers" in the United States — from the top into a seven-column, six-row vertically-suspended grid. The pieces fall straight down, occupying the next available space within the column. The object of the game is to connect four of one's own discs of the same color next to each other vertically, horizontally, or diagonally before one's opponent can do so. There are many variations on the board size, the most commonly used being 7×6, followed by 8×7, 9×7, and 10×7.
The game was sold under the famous Connect Four trademark by Milton Bradley in February 1974.
The game was solved mathematically by James D. Allen (1 October 1988), and independently by Victor Allis (16 October 1988). With perfect play, the first player can force a win by starting in the middle column. By starting in the two adjacent columns, the first player allows the second player to reach a draw; by starting with the four outer columns, the first player allows the second player to force a win.
There are a few programs that claim the ability to play a perfect game of connect four; Mustrum (Lars Bremer), Velena (Giuliano Bertoletti), and TitOT (David Halabi) are three such programs that can be downloaded as freeware.
Variations of playEdit
Newer versions of the Connect 4 gameboard make it easy to remove game pieces from the bottom one at a time. Along with traditional gameplay, this feature allows for variations of the game.
Pop Out starts the same as traditional gameplay, with an empty board and players alternating turns placing their own colored discs into the board. During each turn, a player can either add another disc from the top or — if one has any discs of his or her own color on the bottom row — remove (or "pop out") a disc of one's own color from the bottom. Popping a disc out from the bottom drops every disc above it down one space, changing their alignment with the rest of the board changing the possibilities for a connection. The first player to connect four of their discs horizontally, vertically, or diagonally wins the game.
Before play begins, Pop 10 is first set up differently from the traditional game. Taking turns, each player places their opponent's color discs into the slots filling up only the bottom row, then moving on to the next row until it is filled and so forth until all rows have been filled.
Gameplay works by players taking turns removing a disc of one's own color through the bottom of the board. If the disc that was removed was part of a four-disc connection at the time of its removal, the player sets it aside out of play and immediately takes another turn. If it was not part of a "connect four", then it must be placed back on the board through a slot at the top into any open space and the turn ends, switching to the other player. The first player to set aside ten discs of his or her color wins the game.
In popular cultureEdit
Broadcaster and writer Stuart Maconie – while working at the NME – started a rumor that Connect 4 was invented by David Bowie, which became an urban myth.
- Connect 4 Applet and source code showing Minimax algorithm (German)
- Victor Allis's Master's Thesis containing the solution of the game
- James D. Allen's Expert Play in Connect 4 and upcoming book Complete Book of Connect Four
- John Tromp's history of solutions
- Connect Four television commercial