If she's a goth girl and likes monsters I'm in the camp of check out Alice Copper.
You battle monsters in this game.
Example, when you're in the werewolf mode both you and the werewolf have a life bar (sort of like Street Fighter or Mortal Kombat arcade games).
If you make the intended shot (shots in green) you load your gun with a silver bullet and then have to make the center shot to hit him (which takes life off his life bar).
If you make the shots lit in red, the werewolf bites you and takes your life away.
It's a pretty cool way to battle monsters and keeps dragging me back to play again when they kick my butt.
There are several monsters you battle, Vampire, Pit Monster, Igor, insects etc.
Its really fun and worth checking out if that's the kind of theme you're looking for.

A lot of the suggestions are good, but I would suggest having her play a bunch of these games and see what she likes.