It's a card game that features fantasy monsters. It also contains an Infinity-Deck, with a set number of cards. The only known and shown card in the game is ZapMonChan. That card is mentioned as a ''Ultra rare card'' and it is the last one Candy needs to complete her Monster-mon infinity deck.
In the game, Gravity Falls: Legend of the Gnome Gemulets, it is revealed that Dipper and Candy both play Monster-Mon, and also sometimes with each other, indicating that it's possible to play the card game with multiple people. It's also one of Candy's favorite games to play.
In the game, Candy asks Dipper if he has the Ultra Rare ZapMonChan card. He only mentions that he is to busy with the quest and will come back to her later about it.
The steps mentioning the game on the list are as follows:
- 19 - Display Monster-Mon Knowledge.
- 20 - Do Not Display Monster-Mon Knowledge.
- The card game shouldn't be confused with the 'Monster-Mon' collectable cards in the real-life game 'Kindergarten'.
- 107. "Double Dipper"