There are three variants of this game, but all have the same basic layout.
The deck is shuffled, and each player is dealt eight (8) cards.
The remaining cards are laid face down on the table. They form the “Gene Pool”. When a card is retired (discarded) during play, it is placed face up on a new pile beside the Gene Pool. This new pile is the “Retirement Pile“.
A turn consists of a player taking a card either from the Gene Pool or out of Retirement into their hand and then trying to make a Mating according to whichever variation they are playing. If they can make a Mating, then they lay it down on the table. Because it is important to know who the parents were when it comes time to do the scoring, Matings should be laid out with the parents on top (horizontally) and the offspring underneath (vertically), as shown.
Whether or not they make a Mating, players can discard a single card to the Retirement pile at the end of their turn.
The first person to get rid of all their cards wins the round, and the scores are tallied.
Play can continue for just a single round; until the first player reaches a pre-determined point value; or for a specified period of time.