Connect Four also known as Captain's MistressFour UpPlot FourFind FourFour in a RowFour in a LineDrop Fourand Gravitrips in Soviet Union is a two-player connection game in which the players first choose a color and then take turns dropping one colored disc from the top into a seven-column, six-row vertically suspended grid.
The pieces fall straight down, occupying the lowest 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. Connect four of your checkers in a row while preventing your opponent from doing the same. But, look out -- your opponent can sneak up on you and win the game! 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 Connect 4 9 rules for dating diagonal four in a row, and wins the game.
For games where the board fills up before either player achieves four in a row, then the games are 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 gamesince a player's advantage is an opponent's disadvantage.
One measure of complexity of the Connect Four game Connect 4 9 rules for dating the number of possible games board positions. For classic Connect Four played on 6 high, 7 wide grid, there are 4,, positions  for all game boards populated with 0 to 42 pieces.
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.
Connect Four has since been solved with brute force methods beginning with John Tromp's work in compiling an 8-ply database   Feb 4, The artificial intelligence algorithms able to strongly solve Connect Four are minimax or negamaxwith optimizations that include alpha-beta pruningmove ordering, and transposition tables.
The code for solving Connect Four with these methods is also the basis for the Fhourstones  integer performance benchmark. The solved conclusion for Connect Four is first player win.
With perfect playConnect 4 9 rules for dating first player can force a win, 
Connect 4 9 rules for dating  on or before the 41st move  ply by starting in the middle column.
The game is a theoretical draw when the first player starts in the columns adjacent to the center. For the edges of the game board, column 1 and 2 on left or column 7 and 6 on rightthe exact move-value score for first player start is loss on the 40th move,  and loss on the 42nd move,  respectively.
In other words, by starting with the four outer columns, the first player allows the second player to force a win. Many variations are popular with game theory and artificial intelligence research, rather than with physical game boards and gameplay by persons.
Several versions of Hasbro's Connect Four physical gameboard make it easy to remove game pieces from the bottom one at a time. Along with traditional gameplaythis 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.