Royal Dilemma

A variant of the Iterated Prisoner’s Dilemma where your strength is variable rather than equal.

Materials

• Up to four players.
• A deck of playing cards.

Rules

• Opening
  • Assign each player a face and suit: Ace of Spades, Jack of Clubs, Queen of Hearts, King of Diamonds.
  • Take all the cards that are a face of a player in the game and divide them by suit.
  • Each player gets the face cards of their suit. The remaining numbered cards are value cards.
  • Take the value cards and shuffle them into a deck in the centre. Each player draws a card from this deck and puts it into play under their control.
• Rounds
  • At the start of each round, each player draws cards equal to the number of cards in play under any player’s control. They also draw cards equal to the number of cards in play that are their suit.
  • Then each player can put a face card and a value card from their hand face down in front of them.
  • Cards are turned face up at the same time to reveal the face targeted.
  • If a player targets themselves they are a builder.
    • The builder puts the revealed value card into play under their control.
    • The card is immediately in play and can be captured if the player is being attacked this round.
  • If a player targets another player who didn’t attack them back they invade that player.
    • An invader can choose a card in play under the target player’s control with value less than or equal to their revealed value card and capture it, putting it into play under the invader’s control.
    • If the invaded player has no cards in play under their control, they must instead surrender a number of cards from their hand equal to the value of the revealed value card to the invader, who adds them to their hand. If they have insufficient cards, they surrender what they can.
    • If the suit of a value card is the same as either player its value is doubled.
    • The revealed value card is then returned to the attacker’s hand.
  • If two players target each other, they engage in battle.
    • The revealed value cards determine each player’s strength. The stronger player is victorious.
    • If the suit of a value card is the same as either player its value is doubled.
    • The victorious player then invades the defeated player as described above.
    • The victorious player returns their revealed value card to their hand. The defeated player discards their value card into the discard pile.
    • If the strengths are equal, both value cards are simply discarded into the discard pile.
  • The face cards are returned to each player who played them and then the next round starts.
• Endgame
  • The game ends when there are not enough cards in the centre deck to meet a draw step or no players can take any actions due to empty hands and no cards in play.
  • Points are determined by the value of cards in play under the player’s control, with cards of the same suit as the player being worth double.