In my records, age is but a number that merely depicts how long you have lived in this world and how long you have survived before death. Maturity cannot be compared with age, but surely maturity comes from experience through age. Anyways, it all depends on what he likes to play. As a person who plays all types of games here, I would strongly recommend him to NOT play CoD, but games such as Skyrim, Counter Strike, Battlefield, Far Cry, and other series are great choices. If it's too violent for him (which I think is not), I would strongly recommend him to play puzzle games on par with Portal and Portal 2.