Cuatrola OnLine is a card game app, similar to Tute, where two pairs of players compete. Players are positioned in a cross formation on the game board, with partners facing each other. The game uses only certain cards from the Spanish deck: As, three, Jack, Horse, and King. The game begins with 20 cards randomly distributed among the 4 players, with the suit of the last card dealt determining the trump suit.

Players take turns declaring their intention to play a specific hand or pass. The game follows rules for card plays, including the concept of 'falling' and 'assisting,' with specific point values assigned to different cards and winning conditions based on points or successful hands.