Quake, Doom, Heretic, Hexen 1/2, Red Faction, Sin
That's some good stuff, bro.
STRIFE, make sure to disable all the popamole features if you end up getting the recent re-release.
Good suggestion. Sort of proto- Deus Ex running on Doom engine.
Arguably the best Build engine game. DN3D and Shadow Warrior are good too (DN3D less so) but Blood is the best.
Only played the demo.
Chasm: The Rift, this "Quake clone" uses an interesting engine, it's not a great game though
Still p. good. Nice visuals and good mechanically. Shame about the length and levels being essentially 2D with virtually no z-axis, not even to the extent of Doom engine games.
Yes! A bit linear, but very strong gunplay, cool aliens and strong overall mechanics.
Another legend. Blew everything else out of the water with technical aspects, atmosphere and AI.
Also yes, at least as long as you want some MP or botmatch. Or modding platform.
Then there are tons of great custom maps for
Doom and
Quake.
There are tons of awesome camapigns for Unreal too. Some running in vanilla, some requiring UT.
Anyway some of my own recommendations:
System Shock 1 & 2.
Terra Nova: Strike Force Centauri (although it's more of an outdoor power armor simulator, than typical FPS).
From a bit more modern games, STALKER SoC and CoP.
A decent one too. About DN3D age, suffers a bit from some of the traits Quake 2 has - bland and monotonous environments, and enemies without much personality. Still it has a lot of diverse weaponry and some cool and innovative features to make up for that.
Oh, watching intro will make you cry brain cells - it's so beyond B-movie cheesy.