Dots (game)

Dots (Czech: Židi, Polish: Kropki, Russian: Точки) is an abstract strategy game, played by two or more people on a sheet of squared paper. The game is superficially similar to Go, except that pieces are not taken, and the primary target of dots is capturing enemy dots by surrounding them with a continuous line of one's own dots. Once surrounded, dots are not playable.

Rules

Example of a game beginning

Field

Dots is played on a grid of some finite size, usually 39x32 (this is the size of the grid that is often encountered on a page of squared copybook in Russia) but arbitrary sizes can be used. Players take turns by placing a dot of their own color (usually red and blue) on empty intersections of the grid.

Capture rule

If a newly placed dot completes a closed chain of dots of the same color which encloses at least one of the enemy dots, then all the area inside it is surrounded. To form a chain dots must be adjacent to each other either vertically, horizontally or diagonally. Surrounded enemy dots are added to the score of the player who surrounded them (but his own dots are not counted). All enclosed dots and empty intersection are excluded from further play and can't be used to make new surrounds. To mark a newly surrounded area, surrounding player must draw a boundary line through all his dots that are part of enclosing chain (to make it more visual he can also paint over the area inside it).

Blue can't capture empty area without red dots. Because of this, red player is threatening to play in A and capture one blue dot.

Note, that player can't surround area that doesn't have enemy dots inside. As a consequence enemy can use empty intersections inside it to complete his enclosing chain. However, if enemy places a dot that doesn't finish his own surround, then this dot is immediately captured by a player (this kind of suicide moves are never good but aren't prohibited).

Often there is more than one way of choosing an enclosing chain of dots. When played with pens and paper, players are free to choose one however they like. Nevertheless, when game is played on a computer, to simplify user input, programs usually automatically surround minimum area. In some cases it can be tactically exploited to one's advantage.

Ending

The goal of the game is to capture more dots than opponent. At early stages of game formation Dots was usually played on piece of paper with two pens until one of the players surrendered. However this informal way of ending the game is inapplicable in competitive play. Nowadays almost always a grounding rule is used which is described here.

Continuous groups of dots that touch the border of the field can't be captured no matter how many moves opponent make. These dots are said to be «grounded». At any moment of the game either player can stop the game which is a way to say «All the dots that I want to preserve are grounded. You can take everything else». After that his opponent is allowed to make as many moves as he want to capture all the remaining dots that he can. The game ends and whoever captured most dots wins. In completely lost situation good players usually surrender before his opponent has to explicitly apply this rule.

Initial position

Initial positions that are commonly used (from left to right): cross, double cross, four crosses (only center of the board is shown)

If one of the players will only place his dots touching the border, none of them could be ever captured. To prevent forced draw situations, the game is usually played either from initial position or with first several moves restricted to some area around the center of the field. The most popular initial position is a cross. Other popular ones are double cross and four crosses placed randomly (see pictures). General trend is: the more crosses are initially placed on the field, more active, less probable to end in a draw, and more challenging the game for both players will be.