Heptalion is a special dominoes game played on a diamond-shaped board of 56 squares depicting seven different symbols on them. Two players struggle to place their domino tiles on the board so that both symbols of the tile match with the symbols of the two adjacent spaces on which the tile is placed. The last player placing a tile wins.

The special board configuration has the following properties:

• Each symbol is shown exactly eight times.
• Each domino is shown exactly three times.
• There are exactly 56 squares; the same number of squares that compose the 28 tiles.

A variant for three and four players is included in the rules.