Polyssimo Challenge is a tactical game for 2 to 4 players that contains a 12x11 square board and 24 pieces: the 12 pentominos (all the possible combinations of five squares) and 12 hexominos (some of the combinations of six squares).
To start, players place the pieces in the middle of the table, then take turns choosing one piece after another, placing these pieces in front of them. Once all the pieces have been claimed, the players - starting with the last one to take a piece and reversing the playing order - take turns placing their pieces on the game board one by one. Whoever gets rid of the largest amount of pieces - more specifically, whoever has the fewest squares remaining - wins.
Polyssimo Challenge is very tactical, with an emphasis on geometrical reasoning, as for the Polyssimo puzzle game. Giving a handicap to the stronger player is mentioned in the rules (as in Go), allowing for interesting games even when players have different levels, e.g., a beginner playing against an experienced one.