You may lay cards that match the color (yellow, green, red, or blue) or the number (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) of the middle card. The goal of the game is to be the first to lay down all of your cards. Match cards by color or value and use action cards- you win if you are the first to run out of cards.
Uno Online Multiplayer is a free game with colorful cards.