## Callisto Rules

Callisto is a another board game similar to Blokus. The board is derived from the classic 20×20 Blokus board by removing the corners such that an octagon with a top edge of size six remains. The pieces are a subset of the polyominoes up to size five. They include three 1×1 pieces per player that play a special role.

The 21 pieces

The 1×1 pieces may be placed anywhere on the board apart from the center of the board. The center consists of an octagon with width six and top edge size two. The first two moves of a player must use a 1×1 piece, the third 1×1 piece may be played anytime later.

The board with the center having a darker color

All larger pieces may be placed anywhere on the board but must touch an existing piece of the same color edge-to-edge.

An example position after a few moves

The score of a color is the number of squares on the board occupied by the color not counting 1×1 pieces. Bonus points are not used. Unlike in Blokus, ties are broken in favor of the player who started later.

### Rules for two or three players

The game can be played with less than four players by using a smaller board. For three players, the board is an octagon with width 20 and top edge size two. For two players, the board is an octagon with width 17 and top edge size two. The size of the center stays the same. In addition to the standard two-player variant, Pentobi also supports a game variant for two players like in Blokus, in which each player plays two colors.