A card game was a game played with playing cards. High stakes card games involving gambling required an ante to play.
In 2268, James T. Kirk called the card game which the Iotians were playing a kid's game, in comparison to fizzbin. (TOS: "A Piece of the Action")
In 2366, William T. Riker protested Jean-Luc Picard's suggestion that he host negotiations for the Barzan wormhole rather than Picard, as the first officer felt his poker instincts weren't up to snuff. He believed a card game hadn't prepared him for something of great importance. Picard assured him that a game with higher stakes would be more interesting. (TNG: "The Price")