"UNO is easy to learn but offers players plenty of twists and surprises – making it one of the most popular card games in the world. The goal in UNO is to play all of your cards first by matching cards with the same color or symbol as the top card in the discard pile. Use Draw, Reverse, Skip, and Wild command cards to improve your chances of winning. Just remember to call 'UNO!' when you're down to your last card." Source.
Yeah, it sounds easy. But I found out that it can take hours and hours for someone to win.