Late 90s/early 2000s was a great time.
Quake
Unreal Tournament
System Shock
Half-Life
Deus Ex
Medal of Honor
Halo
Goldeneye
Turok
Just to name several notable franchises. Either multiplayer, single player in story based or immersive sim, or a combination of the first two, there was a lot of to love at the time.

You called down the thunder, now reap the whirlwind







