You could get your son into hack and slash
games, Torchlight (since its a bit more child friendly, less blood etc)
The Diablo series (although thats rated 18+ and contains some scary stuff if you're young

)
Shooters these days have quite a lot of blood and swearing and what not, but if that doesn't bother you, then you could get him into some Quake 3 or something.
I grew up on Doom1, Doom2, Ultima VIII and some other dodgy things I probably should not have played. But I turned out okay

For some reason old school strategy games also do well, thinking of Age of Empires etc, since building an army and attacking stuff was always fun when young.
Hmmm will try and remember some more from my childhood, and pop then down on here
