Connect-Four

Connect Four

Connect 4 game board and box
Designer(s)	Howard Wexler Ned Strongin
Publisher(s)	Milton Bradley / Hasbro
Publication date	1974
Genre(s)	Abstract strategy
Players	2
Playing time	1 - 10 minutes

Connect Four (also known as Captain's Mistress, Four Up, Plot Four, Find Four, Fourplay, Four in a Row, Four in a Line and Gravitrips (in Soviet Union)) is a two-player connection game in which the players first choose a color and then take turns dropping colored discs 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 objective of the game is to be the first to form a horizontal, vertical, or diagonal line of four of one's own discs. Connect Four is a solved game. The first player can always win by playing the right moves.

The game was first sold under the Connect Four trademark by Milton Bradley in February 1974.

Object: Connect four of your checkers in a row while preventing your opponent from doing the same.

The animation demonstrates Connect Four gameplay where the first player begins by dropping his/her yellow disc into the center column of the game board. The two players then alternate turns dropping one of their discs at a time into an unfilled column, until the second player, with red discs, achieves four discs in a row, diagonally, and wins. If the game board fills before either player achieves four in a row, then the game is a draw.

Connect Four is a two-player game with "perfect information". This term describes games where one player at a time plays, players have all the information about moves that have taken place, and all moves that can take place, for a given game state. Connect Four also belongs to the classification of an adversarial, zero-sum game, since a player's advantage is an opponent's disadvantage.

One measure of complexity of the Connect Four game is the number of possible games board positions. For classic Connect Four played on 6 high, 7 wide grid, there are 4,531,985,219,092 positions for all game boards populated with 0 to 42 pieces.

The game was first solved by James Dow Allen (October 1, 1988), and independently by Victor Allis (October 16, 1988). Allis describes a knowledge based approach, with nine strategies, as a solution for Connect Four. Allen also describes winning strategies in his analysis of the game. At the time of the initial solutions for Connect Four, brute force analysis was not deemed feasible given the game's complexity and the computer technology available at the time.