Cripple Mr. Onion

Cripple Mr Onion was originally a fictional card game played by characters in Terry Pratchett's novels Wyrd Sisters and Witches Abroad. This was used by Dr Andrew Millard and Prof. Terry Tao as the basis for an actual card game. The complete rules and design of this game were posted on USENET around 1993. It contains elements of blackjack and poker.

The rules as posted on USENET were approved by Pratchett himself.

The most notable aspect of the game is that it requires an eight-suited card deck: a deck using the normal suits (clubs, hearts, spades, and diamonds) must be shuffled together with a deck using the Spanish (and Tarot) suits (staves, swords, cups, and coins) yielding a complete deck with eight suits.

Each player receives a hand of ten cards: five cards are dealt face-down to each player, and the player may then discard up to four of them, receiving new cards to replace them. Then a further five cards are dealt face-up to each player except the dealer, who receives his face-down. The first player begins by assembling his or her cards into one of the winning groupings described below, and displaying them. The next player must then create a more valuable grouping or fold. If the player is successful in creating a more valuable grouping, the original first player may try again to create an even more valuable grouping for themselves, or fold. This process passes left around the table until only one player remains, who then wins the hand.