In Simon's Cat: Total Mess, the deck is composed of pictures with connected drawings and special "Simon's Cat" cards. Players draw cards and lay them in a row until a card with no number in the corner is drawn. The first player to connect objects from the first to the last card and correctly name the last objects gathers all the challenge cards and keeps them. Players guessing incorrectly return a card to the deck. When a special Simon's Cat card comes up, the first player to shout "Simon's Cat!" wins the card for extra points at the end of the game.

The game stops when all the cards in the deck have been used. The player with the most points wins.