This game is so simple, yet so much fun. The only real rules are to do what it says on the cards and match number to number or color to color. And of course, there is the most important rule: Say "uno" when you only have one card left, and if you don't, don't get caught.
Anyone can play this game, from young nonreaders to adults, and have fun doing it. It can be played pretty much anywhere as well and with two players or more.
There are tons of different versions of Uno nowadays, such as turbo additions and many with cartoon characters on the cards. You can also come up with "house rules, " such as adding something you have to say when you have two cards left.
I still prefer the original addition of this game. It is an oldie but goodie, and it's still just as fun after all these years. Some of my favorite memories of Uno include playing it at the train station in Italy with my brother and saying "Prego" instead of Uno. Also, it was a family favorite when I was a kid, since all of the cousins could play, regardless of age. And, in college, a rousing game of Uno was just what we need to get out of studying. We liked that you could combine decks and make the game last for hours.
I've also played when I worked in a tutoring program, since it helps kids with numbers and colors.