Editing Connect Four (section)

==Rule variations==
There are many variations of Connect Four with differing game board sizes, game pieces, and gameplay rules. Many variations are popular with game theory and artificial intelligence research, rather than with physical game boards and gameplay by persons.

The most commonly-used Connect Four board size is 7 columns × 6 rows. Size variations include 5×4, 6×5, 8×7, 9×7, 10×7, 8×8, Infinite Connect-Four,<ref>{{cite journal|last=Yamaguchi|first=Y.|author2=K. Yamaguchi |author3=T. Tanaka |author4=T. Kaneko |title=Infinite Connect-Four is solved: Draw|journal=Advances in Computer Games, ACG 2011|date=2012|volume=LNCS 7168|pages=208–219}}</ref> and Cylinder-Infinite Connect-Four.<ref>{{cite journal|last=Yamaguchi|first=Y.|author2=K. Yamaguchi |author3=T. Tanaka |title=Cylinder-Infinite-Connect-Four except for Widths 2, 6, and 11 is Solved: Drawn|journal=The 8th International Conference on Computers and Games (CG2013)|date=2013}}</ref>

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 [[gameplay]], this feature allows for variations of the game.<ref>{{cite web|url=https://www.hasbro.com/common/documents/dad2614d1c4311ddbd0b0800200c9a66/DE3C8F8050569047F5AA9FBB9F16909B.pdf | title=C4 Classic Grid | publisher=Hasbro Inc | year=2012}}</ref> Some earlier game versions also included specially-marked discs, and cardboard column extenders, for additional variations to the game.<ref>{{cite web|url=https://www.hasbro.com/common/documents/dad2614d1c4311ddbd0b0800200c9a66/1EF6874419B9F36910222EB9858E8CB8.pdf | title=Connect 4 | publisher=Hasbro Inc | year=2009}}</ref>

===PopOut===
{{Redirect|PopOut||Pop Out (disambiguation)}}
[[file:Connect Four.jpg|thumb|A travel version of the Milton Bradley game]]
''PopOut'' 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 their 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 relationship with the rest of the board and changing the possibilities for a connection. The first player to connect four of their discs horizontally, vertically, or diagonally wins the game.

===Pop 10===
Before play begins, ''Pop 10'' is set up differently from the traditional game. Taking turns, each player places one of their own 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 in an alternate column (whenever possible) and the turn ends, switching to the other player. The first player to set aside ten discs of their color wins the game.

===Five-in-a-Row===
The ''Five-in-a-Row'' variation for Connect Four is a game played on a 6 high, 9 wide grid. Two additional board columns, already filled with player pieces in an alternating pattern, are added to the left and right sides of the standard 6-by-7 game board. The game plays similarly to the original Connect Four, except players must now get five pieces in a row to win. This is still a 42-ply game since the two new columns added to the game represent twelve game pieces already played, before the start of a game.

===Power Up===
In this variation of Connect Four, players begin a game with one or more specially-marked "Power Checkers" game pieces, which each player may choose to play once per game. When playing a piece marked with an anvil icon, for example, the player may immediately pop out all pieces below it, leaving the anvil piece at the bottom row of the game board. Other marked game pieces include one with a wall icon, allowing a player to play a second consecutive non-winning turn with an unmarked piece; a "×2" icon, allowing for an unrestricted second turn with an unmarked piece; and a bomb icon, allowing a player to immediately pop out an opponent's piece.