How is both HL and RF gory?
The original Doom is still pretty much the goriest sprite FPS ever, or for newer ones, play Quake 4.
Actual scene from Quake 4:
Yay! Amputation scene in first person! With a rusty chian saw! Doesn't get sexier than that.
Back on topic, Red Faction had a good storyline (same goes for the sequel), and the physics engine was awesome for the game of that time.
Plus, the enviornment damage system was pretty original, although some people on multi-player basically "dig" a hole in the wall with a Rocket Launcher, hide themself inside the hole, and whore the Rocket Launcher from inside for offense/defense.