Connect Four (also known as Connect 4, Four Up, Plot Four, Find Four, Captain's Mistress, Four in a Row, Drop Four, and Gravitrips in the Soviet Union) is a game in which the players choose a color and then take turns dropping colored tokens into a six-row, seven-column vertically suspended grid.

The objective of the game is to be the first to form a horizontal, vertical, or diagonal line of four of one's own tokens.

The game was created by Howard Wexler, and first sold under the Connect Four trademark[10] by Milton Bradley in February 1974.

Connect Four also belongs to the classification of an adversarial, zero-sum game, since a player's advantage is an opponent's disadvantage.

For classic Connect Four played on a 7-column-wide, 6-row-high grid, there are 4,531,985,219,092 (about 4.5 trillion) positions[12] for all game boards populated with 0 to 42 pieces.

Connect Four has since been solved with brute-force methods, beginning with John Tromp's work in compiling an 8-ply database.

[13][17] The artificial intelligence algorithms able to strongly solve Connect Four are minimax or negamax, with optimizations that include alpha-beta pruning, move ordering, and transposition tables.

The code for solving Connect Four with these methods is also the basis for the Fhourstones[18] integer performance benchmark.

With perfect play, the first player can force a win,[13][14][15] on or before the 41st move[19] by starting in the middle column.

[21] Several versions of Hasbro's Connect Four physical gameboard make it easy to remove game pieces from the bottom one at a time.

The first player to connect four of their discs horizontally, vertically, or diagonally wins the game.

Gameplay works by players taking turns removing a disc of one's own color through the bottom of the board.

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 in an alternate column (whenever possible) and the turn ends, switching to the other player.

The game plays similarly to the original Connect Four, except players must now get five pieces in a row to win.

Connect Four was released for the Microvision video game console in 1979, developed by Robert Hoffberg.

Just like standard Connect Four, the object of the game is to try get four in a row of a specific color of discs.