OXx is a game system with cards. The rules contain four ways of playing, the publisher has announced that further rule sets would be published on their website. The cards have three properties: A background color, a word (blue, yellow, etc.) and a color in which this word is written. Most rule sets are based on finding cards with two matching characteristics, you will then try to get rid of them by stacking them up, either player by player or in a speed mode.