Hydra

Hydra is a card game created primarily by Gregor Richards and Michael Goss, with a few rules thrown in by others and lots of playtesting thanks to their friends. In the game of Hydra, the goal is to lose all of your cards, by placing them on a large (and increasing) number of piles on the table, each called a head. Each pile is called a head because, like the mythical Hydra, each time a head is removed, two new ones grow. For instance, in a three-player game it is common for there to be 25 heads by the end of the game. Each time a head is removed, all of its cards are added to the cards of the offending player, who must then play two new cards to create the new heads. Although the rules are relatively simple and the game could be learned and enjoyed by people of any age, this style of expanding playing area allows for complex strategy. The strategy comes in the sheer number of options provided: with a dozen potential places to put any given card, one must carefully consider what affect a move will have on oneself and on opponents, while also considering when and how to end the current turn to minimize risk. For advanced play, card-counting is not just allowed but a must, with a decent knowledge of the content of each head necessary for deep strategy.

== Rules

There should be about one deck of cards per player in the game. Each deck should have exactly one joker.

During play, there are a large and increasing number of piles on the table, each called a head. These should be arranged in a snaking fashion, with new heads placed at the opposite end of the oldest ones, to make it clear which heads are old and which heads are new. Each player has a draw pile and a discard pile, both face-down. The discard pile is initially empty.

Shuffle all of the decks together, then distribute the cards evenly amongst the players' draw piles. Decide who will go first as you please. Before the game begins, each player places one card from the top of their draw pile face-up in a row at one end of the table, forming the initial heads.

During each turn, the player draws cards, one by one, from their draw pile, trying to place each on a head. The number of cards the player may at most draw in a turn is the number of heads; e.g. the player draws six cards if there are six heads.

Upon each card draw, the player may do one of three things:
 * Place it on any head with a card of greater value, and continue;
 * Place it on any head with a card of equal value, and end their turn; or
 * If its value is greater than that of the oldest head in play, place it and the oldest head in play into their discard pile, then place two cards from the top of their draw pile into two new heads at the opposite end. This also ends their turn.

Note that if the card's value is greater than the value of //every// head, then only the third option can be used, ending the player's turn. The player //must// continue drawing cards up to the number of heads if the first option is invoked, but //must not// continue drawing cards if either of the next two options are invoked.

Because of this placement method, the line of cards will slowly move down the table during the game. It is usually necessary to make a snaking pattern of cards to keep them all on the table.

A player may shuffle their discard pile into their draw pile at the beginning of any turn. If the number of cards in their draw pile is less than the number of heads, however, then they //must// shuffle in their discard, since otherwise they could run out of cards.

Aces may be played on any card (they are lower than every card), but any card may be played on them (all other cards are lower than them).

Jokers are wildcards, and their value is chosen when they are placed. The play must still be valid for whatever value is chosen, however (e.g. one can't declare a joker to be a king then play it on a three). The value remains fixed until the joker is discarded.

Though not required by the rules, it is highly recommended that players separate the number of cards that there are heads from their draw pile at the beginning of their turn, so they don't have to maintain the count. If their turn ends before all the cards are played, then the separated cards can simply be added back to the draw pile.

== Optional rules

This rule is optional; with or without it the game involves a fair amount of strategy, but reserves add another dimension of strategy.

=== Reserves

This adds a new pile, the reserve, to each player. Initially empty, the reserve is a face-down pile, used as a backup to the normal card draws. It adds the following new options to the "upon each card draw" section above:
 * Place it on top of the reserve (this may only be done once per turn); or
 * Before playing the card drawn, play the card from the top of their reserve pile using any of the previous rules. If the play ends their turn, then the card drawn from the draw pile is discarded, and it is never used as a new head.

A player may look at the //top// card in their reserve at any point, but must simply remember (or not) the rest. To win, the player must have both an empty draw pile and an empty reserve; if they have an empty draw pile but cards remaining in the reserve, then the reserve must be played through, in order, one card at a time, using any of the first three play rules.

== Legal

The text of these rules are copyright Gregor Richards and Michael Goss, 2008-2010. You may copy them only for non-commercial use. Any other use requires explicit license.