Fallout might be a little too graphic, but Halo if it's an xbox definately for movement and aiming skills...
There's an awesome game called Skyrim out there (Sarasm meter high) that isn't too graphic (I believe there's settings if you're worried about that)... Every gamer I know has played the ElderScrolls at least for 3 hours, so y'know what I mean. Assassins Creed I found is a not too violent (heheh but seriously, I got more scared of Halo thaan AC) but it's pretty easy to understand with pretty good tutorials and forgiving respawns (so you don't rage alot)... OR just buy him a gamecube and buy all the old-school Zelda games. That's how my grandparents got me into gaming (yus, my parents weren't fond of it...)
Also, if you're going to build him a PC, you should start talking about whaat type of gear he'll want (i.e. Mechanical switches, Razer, Corsair, Logitech, Razer, etc)... Just a good converstion starter. Who knows?! He might not even like PC games. I have a few friends that use controllers for everything.
NOTE: If there's any spelling errors, don't hate plz... My keyboaard is giving me issues (TIP: Don't spill waater on a mecchaantical keyboard...)
-LukeS
I_M_3rd