Some of the call of duties have a coop mode called spec ops/zombies,they're pretty fun. minecraft, terraria, Lego games, Street fighter, Driving games? There are loads mate, just got to know what type of games he likes.
If your willing to spend Skylanders and Disney Infinity are options. I got Skylanders for my nephews and they play them at their house and then bring them here to play on my console (figures level up cross platform too so level on Wii and then play on Xbox).
I might get Disney Infinity 2.0 when its out as its all the Marvel characters from Avengers, Spiderman, Guardians of the Galaxy etc and now Disney own Star Wars I guess that may come in the future too.