Mario Bros from nintendo got ALOT of people hooked on video gaming, myself included!
Wolfenstein, Doom, Quake...early FPS brought that era into being, though I think the early Contra games had a little something to do with that...not FPS but still lots of shit to shoot at!
Pong of course should be at the top of any list...wasn't the VERY first video game but the one that brought video games into people's homes!
R.C. pro am very good early racing game along with pole position brought in the racing era!
Mortal Kombat for the blood and violence era!
EVERY video game today can trace it's lineage back to either nintendo or atari for it's roots! They came from very humble beginings!