Players compare the numbers in multiple regions, as well as the numbers harvested along each path. The difference between the players' numbers determines the score; numbers belonging to only one player do not count, and becoming an Isolated Piece incurs a penalty and awards points to the opponent. The players' scores are opposites of each other, A positive score wins.
Each piece is a square. Each player has five pieces of each of the following five types:
Single One: one solid edge and one triangle.
Double Two: two separated solid edges and two triangles.
Corner Two: two connected solid edges and two triangles.
Surround Three: three solid edges and three triangles.
Cross Zero: two diagonals crossing inside the square.
Every piece's triangles face its solid edges, except that a Corner Two's two triangles face the corner formed by its two solid edges.
The board is a seven-by-seven grid. The centre square is marked with a dot.
The first player must place a Corner Two on the centre square.
Every later piece may be placed freely on any empty square.
Two solid edges may not overlap along the same grid line.
The first player must place twenty-five pieces and the second player must place twenty-four.
The second player must leave one non-Cross-Zero piece unplaced at the end. This piece becomes the Isolated Piece, and its triangle count defines the Isolation Value for this game.
After placement, the second player harvests first. The players then alternate until each has removed all five of their Cross Zero pieces.
On each turn, choose any friendly piece as the starting piece, including a Cross Zero.
If a non-Cross-Zero piece is selected, move it according to the direction its triangles face: a Single One moves one step forward; a Double Two chooses one direction and moves one step; a Corner Two may land on the first or second piece encountered diagonally; and a Surround Three chooses one direction and moves one step.
Every move must land on a piece, and empty squares may be passed over. A Corner Two may also jump over the first piece encountered and land on the second piece along its diagonal. A move cannot leave the board.
During one harvesting turn, pieces harvested earlier are immediately treated as empty squares, and later pieces may pass over those squares.
The path must finish on the acting player's own Cross Zero. All pieces in the completed path are removed.
If the turn removes only a single Cross Zero, that piece is a Isolated Cross.
Placement scoring:
The pieces' solid edges and the board boundary together divide the board into multiple regions.
If a region contains pieces from both players, the difference between their triangle counts determines the scores for both players.
If a region contains pieces from only one player, no points are scored.
If a piece is trapped inside a single square, it becomes a Isolated Piece: its owner loses points equal to its triangle count, and the opponent gains the same amount.
However, if a piece's opening is adjacent to a Cross Zero, it does not become a Isolated Piece, because there is an extra quarter-square of space.
At the end of the placement phase, points equal to the Isolation Value are deducted once from the second player's score and awarded to the opponent.
Harvesting scoring:
Each harvesting turn is scored separately.
Within the pieces harvested, the score for that turn is the friendly triangle count minus the opposing triangle count.
If the turn harvests only the acting player's own pieces, it scores zero.
If a Isolated Cross is harvested, points equal to this game's Isolation Value are deducted directly.
Determining the winner:
The players play two games; the side whose final score is positive wins.
In either game, a player who cannot place or harvest according to the rules loses immediately.