Share it with your friends and play it online together! How to play Uno Online online? Use special cards to block your opponents, and clear your hand to win! Don't forget to say 'UNO' (press '1') whenever you have your last card at hand, otherwise you will be punished with two penalty cards. You can play Uno with 2, 3, or 4 players. Your main objective in Uno Online is to be the first player with no cards. Uno Online is a board game where you play the cards in your hand which match the pile by either color or number.