Enclave

Definitions

Region: any distinct area of the board, consisting only of empty points, and surrounded by one color of stone in conjunction with at most 2 board edges.

Loose stone: any stones not outlining a region. Loose stones are captured when surrounded by an enemy region

Objective: Control the most territory (stones + regions). The game ends with two successive passes

Gameplay: Players alternate placing a stone of either color on an empty point of the board. If doing so forms any regions the following conditions must be met:

 all enemy stones within the prospective regions are loose stones.
 there must be at least one loose stone in each prospective region to be captured.

Note: You may never play stones into an established region

Pie Rule: On his first move, the second player may opt to play as the opposite color in lieu of making a move.

—description from the designer