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Two players race to be the first to obtain three Chaos Emeralds. The game is played with each player having two rows of five cards each, arranged so that they form columns with the opponent's cards (in essence, a 5x4 grid). The row closest to the player is called the chaos row, while the row closest to the opponent's cards is called the spare row.
After each full turn, a single Chaos Emerald may be earned by one of the two players. The Chaos Emeralds themselves are abstract entities not represented by the cards, so players are encouraged to use coins or other tokens to track them.
Players start the game by drawing seven cards each from their decks, and then randomly determining the lead player. Turns consist of a number of steps, with each player acting in each step. The steps are as follows:
- Play Step - Each player places five cards from his or her hand face-down into his or her chaos row. Players can always look at their own face-down cards, but not those of their opponent.
- Rush Step - The lead player flips a card face-up from his or her chaos row, and the other player then does the same. Players cannot flip cards over in the same column where their opponent just revealed a card, unless they have no other choice. Players continue to alternate revealing cards until all of them have been revealed. As cards are flipped face-up, they may cause other cards to be discarded.
- Score Step - Each player adds up the total rings from face-up cards in his or her chaos row and spare row. If one player has more rings than the other, that player wins a Chaos Emerald, with neither player winning one in the result of a tie.
- Recharge Step - Both players draw cards until they have seven cards. After this is done, cards in the spare row are discarded, while cards from the chaos row are moved into the spare row (but within the same column).
After each turn completes, the player who was not the lead player becomes the lead player for the following turn.
- Title - The title of the card, used for uniqueness purposes when constructing a deck and referred to by certain other cards.
- Traits - Keywords underneath the title which other card effects may act upon. The base traits are Animal, Human, Place, Robot, and Thing.
- Color - Cards can be blue, red, yellow or gray in color.
- Number Key - Information for collectability purposes, including the card number and rarity, which appears in the upper right corner.
- Rings - The large number on the card which represents the number of rings associated with that card.
- Text - The actual text near the bottom of the card which causes game effects.
As cards are revealed during the Rush Step, the act of flipping over the card may cause the opposing player to discard cards from the card grid. This is based on two discard rules:
- Copy Discards - When a card is turned face-up, if the opponent has any face-up cards (anywhere in either of the two rows) which have both the same color and the same number of rings, these cards must be discarded.
- Battle Discards - When a card is turned face-up, if the opponent has any face-up cards of the same color in the same column, check the number of rings on those cards. If a rival's card has more rings than the card just revealed, it must be discarded. Note that there is a limit on one discard at a time triggered in this fashion (i.e. flipping one card face-up cannot cause a Battle Discard from both the opponent's spare row and chaos row at the same time).
It is worth noting that the actual text on the card itself may cause further discards or otherwise have further instructions (e.g. "When flipped, you may discard an opposing blue card").
Hence, the primary play strategy has to do with the arrangement of cards (particularly against the cards of an opponent's next spare row, which is known from the previous turn), and with the order in which cards are revealed.
Decks and cards
Each player must provide a deck with at least thirty cards. There is a limit of five copies of any single card per deck.
Cards can only be purchased in booster packs, which contain ten cards each. Thus, a minimum of three booster packs is needed in order to build a playable deck, although because there are no cards of differing types, it is quite likely that three boosters will be sufficient.