There was a different thread about our kids playing games, but my now-6th grader enjoys playing 8-bit and 16-bit games, including Gameboy...and whatever classic arcade games we can find:
Recently (last 6-12 months, ha!)...
Pokemon
Dr. Mario
Parasol Stars
Galaga/Galaxian
Joust
Gyruss
Balloon Kid
Kaboom!
Bonk 1-3
Monster Lair (co-op, I help her survive)
Mario (all)
Mariokart
Ninja Spirit
Star Parodia
Etc.
Get an Atari VCS and play Tank Pong with him. He'll love it.
I have Atari 2600
Kaboom! and Joust are on list (although we play NES version of Joust, too).
We have played COMBAT, but not in the last year.