Monsta has 81 cards featuring cartoon monsters and a number between 2 and 7. The active player plays a number of identical Monstas from his hand equal to the number featured on those cards (e.g. two 2s or six 6s); one is kept in his scoring area and is worth a number of points equal to the number on the card, the rest are discarded.
The top card of the draw pile is then revealed, the active player adds any one card from his hand, and the remaining players secretly bid cards from their hands. Cards from the highest bid go to the active player and the highest bidder takes the revealed cards and becomes the new active player. First player to 15 points wins.