I know what you mean, a game hasn't really been able to engross me like it did say, 5 or 6 years ago. I don't feel like I'm suddenly too mature for games or anything, but... I dunno, they just aren't the same. I'm a big RPG fan, I can only get into a few shooters, and never for long.
One game I did spend many many hours on was Borderlands though, a great mix of shooter and RPG and loot mania. I highly recommend that game.
I wish I could get into a game like I did between 12-20 though. It was magic back then, especially at the start when game were just getting good. When all of a sudden the graphics exploded into greatness(now, total crap, but then mind blowing). Games had stories, not great stories, but stories that got you involved with the characters and plot. Now they all kind of feel gimped and boring.
Sigh.