I'd say borderlands (2). It's simple (point, shoot, walk), it has a pretty immersive story (at least IMO) and probably the hardest parts are redeeming your tokens and comparing your weapons...
I wasn't sure whether that one quite fits the OP's criteria, but now that I think about it I've actually been very impressed by BL2's story delivery so far (Handsome Jack = Best. Villain. Ever.).
Revan avatar by kaptainkrutch.
Originally Posted by Cirrylius
That's how wizards beta test their new animals. If it survives Australia, it's a go. Which in hindsight explains a LOT about Australia.