From the publisher:

Triolet is a numbers games in which the objective is make "15" with three tiles on a board.

Players lay 1, 2, or 3 tiles intersecting crossword-style on a board. Additional points are scored when three tiles equal 15 or all three tiles are placed in one go. It's an easy game to learn and the "double", "triple" and "bis" squares ensure that players who have started slowly can catch up. When the tiles run out, the game ends and whoever has scored the most points wins.