Data Structures: The Card Game

This is a card game, created by Gregor Richards and Harrison Metzger. It is absurdly complicated.

== The data structures

=== Deck
The game is played with two standard 52-card decks.

=== Queue
In the center of the table is a queue. The queue has a maximum of five cards, and moves in a predetermined direction. The stack of cards is placed at the beginning of the queue to indicate its direction. The cards in the queue are face-up.

=== Stacks
Each player has a stack. The stack is face-up in front of the player.

=== Hands
Each player has a five-card hand.

=== Arrays
Each player has three arrays. The objective of the game is to get all three arrays to have every value (2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K) in order. The lists may start with any value, but must loop back 'round to one less than that value.

== Setup

At the beginning of the game, the deck is placed to one side. All five cards of the queue are set out, as are a single card for each stack, and each player's five-card hand.

== Gameplay

The game is a turn based game. Each players turn can be divided up into phases.

=== Phase 1 (Play)
During this phase, the player can use any card from their hand, either of the 2 stacks, or the head of the queue to place the next card in sequence on one of his arrays. An array can only be started from a card in the player's hand. Should an array become complete on a card move, the array is turned upside down (so all cards are now face down) and will be shuffled back into the deck in phase 3.

Any time the player uses all 5 cards in their hand, they are allowed to redraw all 5 cards. Likewise, should all 5 cards in the queue be used, it is refilled from the deck.

Alternatively, should the player be unable to play any card at the beginning of phase 1 (this is verified by showing all cards in the hand to the opponent), they may choose to discard 4 out of the 5 cards in their hand. This ends phase 1.

=== Phase 2 (Discards)
Phase 2 begins by discarding the head of the queue. The player removes the head of the queue and places it on the discard pile.

The player then must place one of their cards on their stack.

Should the player have any cards in their hand and the queue not be full, they can optionally put cards from their hand into the end of the queue.

=== Phase 3 (Replenish)

Should any arrays be closed, they, along with the discard pile, are shuffled back into the deck.

At this phase should the queue be less than 5 cards, it is replenished by drawing from the deck.

Also, the player's hand is replenished to 5 cards.

An invariant is that on the beginning of each player's turn, both players have 5 cards in their hand and the queue is filled with 5 cards.