Hmmmmm. How about Braid? It's a relatively simple platformer (...well, until you get to the later levels), but it's incredibly beautiful and has a remarkably deep, complex story. And a kickass soundtrack.
And in the same 'simple but gorgeous' vein, Limbo. It's one of the best games I've played this year, and it's the understated quality that makes it so good. It has a very surreal, dreamlike quality, and the animation reminds me of shadow puppetry.
Braid is one I was thinking of mentioning, too (for the same reasons you stated).
STALKER
metro 2033
amnesia dark descent
mount and blade warband
deus ex human resources will be out by then
minecraft (i just started playing this game and its freaking awesome)
star craft 2
I think STALKER has too many complications and stuff. Keeping track of what you're doing, where you need to be, dodging anomalies.... too much. Maybe when she's got a solid grounding and is fairly confident with FPS's.
M&B occurred to me, but it'll be a while before she's ready for the combat (and combat is 90% of the game). The player is rather fragile early on, due to both low skill and lack of gear.
I gather
Penumbra (preceded
Amnesia, so I'd go with it first) is is largely just mental work (little need for reflexes, etc.), so it'd be an option, if she's up for a psychological (you get scared, not startled) horror game.
Haven't played/don't know much about the others.