Pokémon.
Well, it's been around for about 13 years. When it first came out it was all the rage. Even now kids and adults alike play it casually and competitivly.
Pokémon appeals to everyone. From casual, to intense gamers. From young kids to adults. There is hardly a place, in the U.S., that people don't play Pokémon.
Don't forget the card game. I am just collector, but there are others who battle and compete with them. Others maybe, collect them just to sell them. [my hobo is trying to persuade me to do that] But nonetheless, the cards are somthing to do if you're a big Pokémon fan like me.
Still, for the people who don't have the time to play the game, or have the patience to collect the cards, there is the anime series. It has stretched on for 15 seasons and about 13 movies. You know the story, Ash befriends Pikachu and they go on an adventure throughout the Pokémon world.
For the people who haven't tried Pokémon here is a list of the reigons and the games they go to.
P.S. I Pokémon!!! I've been playing it since I was 3.