Perpend is a connection game for two players: Black and White. It is played on the intersections (points) of an initially empty square grid (board). The top and bottom edges of the board are colored black; the left and right edges are colored white.
Black plays first, then turns alternate. On your turn, place one or two friendly stones on empty points. If you place two, they must be orthogonally adjacent to each other. Next, place enemy stones on all secluded empty points. A point is secluded if there is no free path along the lines of the board between that point and the edge of the board.
At the end of your turn, for any two diagonally adjacent stones of your color there must be another stone of your color adjacent to both, and there must be no 2×3 patterns of two empty points, two black stones a knight's jump away from each other and two white stones a knight's jump away from each other. Passing is not allowed, but, if you have no legal moves available, your turn is skipped.
You win if there is a chain of orthogonally connected stones of your color touching the two opposite board edges of your color.
To make the game fair, White will have the option, on their first turn only, to swap sides with Black instead of making a regular move.
-description from designer