What's Your Cosmo? is a set of custom playing cards that are used to play a variety of games that range from easy to difficult and from 1 to 6 players. There are seven unique card games using double-sided playing cards, two different wild cards, positive and negative signs, letters, and five title cards. The object of each game involves making triples, straights, equations, or completions. In addition, the COSMO game system (a set of standard and customizable rules for games that use the What's Your Cosmo playing cards) provides plenty of space for ingenuity to create and design fun, new games. The COSMO deck is one hundred cards. The dark side of the cards features one of the numbers 1 through six or -1 through -6. Each number appears six times. There also are Sun and Infinity wild cards. The light side features one of the letters C, O, S, or M, with the O appearing twice as often as the other letters. Instructions are included for seven games, including solitaire and a children's game. Many of the games involve building sequences or sets; others use simple math. Games that use only the light side of the cards tend to be variants on spelling COSMO or finding the letters in COSMO.