Long story that I'll try and cut short:
I've been gaming since about 1995, obviously I really enjoy it, but a couple of years ago I got a little burned out from it. I was playing World of Warcraft at the time and I mixed in some JRPG's like FF XII and Wild ARMs 3. All fantastic games, but they just left me a little tired of gaming.
Two games got me back into it and they were: LittleBigPlanet and WipEout HD Fury. It was the first time I'd really embraced the current generation. I got my PS3 in 2008 to play Metal Gear Solid 4 but then I didn't really use it for about a year because I was still playing all my favourite games on PS2/GC.
Anyway, the thing about both those two games that I think got me back on track was the way they're designed. They're both simple concepts (2D platforming, racing) that are really easy to learn but the games themselves were pretty deep. WipEout is a fucking hard game to master, but it's easy to pick up and play as just a racer. Same with LBP - easy just to bounce your way through the platforming levels, but there was so much more there with all the content creation and what not. Both games just mixed the simple with the deep really well.
I don't see myself tiring from gaming again any time soon because I've got myself back into the swing of it now, which is good at least.