pokemon
Once a very popular TV Show, Card game and video game which I myself was quite a fan of at the time. The TV Show and Card game sort of fizzled out after Poke'mon had had its time but the games were very good and they still exist to day. Of course I'm always seeing new card series's being brought out and am occasionally mildy interested because the artwork on some of the cards was rather good. In fact the card game was very popular and a lot of fights broke out about people not trading fairly and people even resorted to stealing others cards but I knew it had all gotten out of hand when at my first school they had people to watch over the swapping of Poke'mon cards and advising people on good swaps. Eventually most schools banned Poke'mon cards (and any others for that matter). So, when they began bringing out all those new Poke'mon and card sets it got a bit boring. So all in all the original Poke'mon cards, games and possibly the TV series was a rather good achievement but it never managed to keep a lot of fans after a few years, but, of course there are still dedicated Poke'mon fans all over the world.
When Poke'mon was cool: 

Person 1: Whoa look I got this Japanese import of Venusaur!

Person 2: Oh well cool! Swap it for my shiny Clefairy!?

Person 1: No way!