Carteso
Description
Carteso is a finite territory game for two players: Vertical and Horizontal. It is played on the intersections (points) of an initially empty square grid (board). The suggested board sizes are between 9x9 and 13x13 points. Both players must have access to a sufficient supply of stones in two colors and vertical and horizontal markers.
Carteso was inspired by a conversation with Corey L. Clark. The game's name was suggested by David Stoner.
Definitions
A group is a stone along with all stones one can reach from it through a series of steps onto adjacent stones of its color.
A group, regardless of color, is owned by Vertical if it spans more rows than columns, and by Horizontal if it spans more columns than rows. Groups that span exactly as many rows as columns are owned by the opponent of the player who most recently placed a stone on the board.
To claim a group is to place a marker of yours on top of one of its stones.
A group is finished if its vertical and horizontal dimensions cannot grow larger by means of any series of placements on empty points.
Play
Vertical plays first, then turns alternate. On your turn, pass or place a stone of any color on an empty point. After a placement, let every unclaimed finished group be claimed by its current owner.
The game ends when both players pass in succession. The player with the higher score wins. Your score is the total number of stones on the board in groups you have claimed, plus komi in the case of Horizontal. The button is used to avoid ties.
Komi and button
Komi is the whole number of points that is added to Horizontal's score as compensation for going second. Before the game starts, the first player chooses the value of komi, and then the second player chooses sides. Alternatively, experienced players may agree on a standard value for all games.
The button is a special token that is placed next to the board at the start of the game. On your turn, if neither player has taken the button yet, you may not pass, but you may take the button instead of making a regular move. At the end of the game, a half point is added to the score of the player who has taken the button.