In order of release (These are what I think the revolutionary games were/are):
1) Space Invaders (ARCADE, 70s)
2) Pac-Man (They even made a song and a cartoon about it)
3) Donkey Kong (The precursor to Mario Bros & Super Mario Bros)
4) M.U.L.E. (One of the first popular economic simulators)
5) Rescue on Fractalus/Behind Jaggi Lines (One of the first well programmed 3D PC games)
6) Super Mario Bros. (Remember playing this as a teen)
7) Sim City Series of games (obvious...)
Flight Simulator 5 and above (If you have any affinity towards airplanes)
9) Hard Drivin' (Was a revolutionary driving simulator, came out in early 90s)
10) The entire GTA series of games (Violent, but the modeling of the cities are top notch)
It's really been amazing to grow up alongside the video gaming industry, it's changed so much from when I was a kid, and I'm looking forward to seeing what the future has in store for us all.