そすーと (Sosuto)

Sosuto is a climbing game based on prime factorization. Play proceeds clockwise and on your turn you must, generally, play a higher card than the last person. You may play any higher card that shares a prime factor with the last card played; you may also play a lower card if it is one of the prime factors. The cards are color coded to aide in the math. A round ends when either a player has played all of their cards, or a player has collected a certain number of penalty cards from not being able to play. Players lose points based upon the cards left in their hand. The player with the most points after a series of rounds wins.