Setup. The board is a hexagonal diamond of 25 cells. The middle row of five cells starts empty and belongs to neither player. Each player begins with 20 tiles stacked in a pyramid on their own half — rows of four, three, two, and one from the middle outward. White moves first. Pie rule: after White's first move, Black may either reply or swap sides and take over the White position.
Movement. A move lifts one entire stack you control (your color on top) and sows it in one of the six directions: the sow advances one cell at a time, dropping the bottom tile of the lifted pile onto each cell it enters. Cells holding your own tiles are entered normally, at any height; the dropped tile lands on top.
Walking the heights. The sow stands on top of the last tile it placed — at the moment of lifting, on top of the tower as it stood. From where it stands it may step level or downhill, never uphill. Your own stacks are always open ground, at any height.
Boarding. An enemy stack no taller than where the sow stands may be entered: the dropped tile covers it, control of that stack passes to you, and the sow walks on from its new top. Dropping onto low ground lowers you — a tall tower keeps its reach only while the ground beneath it stays tall.
Turning. Board edges and enemy stacks taller than where the sow stands are walls. A walled sow turns toward the open direction closest to its heading. If every direction is walled, the remaining tiles pile where the sow stands.
Objective. You win when every cell you control lies on the middle row or in your opponent's half, and those cells form one connected group of at least five. If both players complete unification on the same move, the player controlling more tiles wins.
Constraints. Passing is not allowed. No move may recreate a previous position. A player with no legal move loses. A stack with no legal move is permanently trapped (marked ⊘); it still counts among your cells, and therefore blocks unification.