Каллисто - это еще одна настольная игра, похожая на Блокус. Доска получена из классической доски 20×20 Блокус путем удаления углов таким образом, что остается восьмиугольник с верхним краем шестого размера. Кусочки представляют собой подмножество полимино до пяти элементов. Они включают в себя по три фигуры 1×1 на игрока, которые играют особую роль.
21 Фигура
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.
Доска с центром более темного цвета
All larger pieces may be placed anywhere on the board but must touch an existing piece of the same color edge-to-edge.
Пример позиции после нескольких ходов
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.
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.