Setup
Use a hexagonal board of any size and topology. A hexhex board of size 4 is recommended. Also have on hand plenty of stones in two colors.
The Pie
Player one places any number of stones on the board in any arrangement. At least one stone placed must be black. Player two selects the color they would like to play. Then the game begins.
Gameplay
There are no turns. At any time a player may place a stone of their own color on an empty space subject to the following restriction: the newly placed stones must have strictly more sight-lines to enemy stones than to friendly stones. It is illegal to place a stone which cannot see any other stones (as the comparison is zero versus zero, which is not a strict majority).
A Sightline
For completeness, a stone has a “sightline” to another stone if there is a straight line of empty spaces between the two stones or if the two stones are directly adjacent. Thus, a stone may have up to six sightlines.
Game End and Scoring
The game ends when neither player wishes to play any more stones. The player with the largest connected group of stones wins. If there is a tie, compare the second largest groups for each player, and so on. If a player runs out of groups for this comparison, they are considered to have an infinite number of "0-size" groups.
The red player is considered to have an additional, imaginary, "1/2-stone" group for the purposes of scoring. In other words, if the game is otherwise a draw, the red player wins.
—description from the designer