The game is played with a standard deck of playing cards, a special record sheet, and alien character cards. The sheet tracks damage to various parts of your alien's brain. There are six different aliens, each with a different special power.
Different ranks of cards allow for attacks of varying strength. The suit of the card determines which region of the target's brain is effected. For example, the 3 of Hearts can power an attack against the opponent's brain stem that does one pip of damage. Cards can also be used to defend against attacks.
If a region of the your alien's brain is disabled, you lose abilities. For example, you may no longer defend if the brain stem takes too much damage. If a second region is disabled, you lose the game.
Card management is important, because you don't automatically draw cards to replace ones that you've played. You may take a turn to 'focus' and refill your hand, but you don't get to attack.