My then-girlfriend was one of the giggling "give-it-a-try-to-make-bf-happy" types, albeit a bit of a nerd already. Imagine my surprise when I booted up L4D, and she proceeded to, in the span of a single act, master first-person movement, learn all the controls forwards and backwards, and become a fairly decent marksman. She wasn't quite on my level, but my play experience can be measured in years, while hers was measured in HOURS. (And for those who think first-person games are simple, go check out Shamus Young's blog posts on the subject. That man is a better writer than I could ever hope to be.) Also, my younger sister just made it through her first full round of Hunter in Splinter Cell: Conviction, and fired the game-ending shot.