Ultima IV and V
DOOM (original)
Quake I and II
Civilization (I-V)
Total Annihilation
Alone in the Dark
Planescape Torment
Ultima Online
Halo (PC)
Half-Life 2
Shadowbane
Games I grew up with. Games that either showed there were more than just kill boss to win (Ultima IV and V), or the immediacy of a first person word in shoot em ups.
The 4X genre was made for me by Civ I, I taught my father how to use a PC with Civ 2 ( he had to learn DOS commands to start it up), he would have never used a computer otherwise.
Ultima Online because it was a giant freaking multiplayer sandbox.
Halo and Half-Life 2 for being just right and fun.
Shadowbane (I know, an MMO) for showing a buggy pile of shit can be so much fun the playerbase can destroy itself out of a game. HING4LIFE.