hidden gems of fps genre

[patho]

As an fps fan, I'm always looking for relatively unknown games of the genre.

What are your hidden gems?

PC
Shadow Ops: Red Mercury [good fps]
Shanghai Dragon [it's not an fps, it's an on-rails shooter. a very unknown but very fun game.]
Dead Man's Hand [good fps]
Nitro Family [good fps]
Vivisector: Beast Within [average fps, it's fun.]
Pariah [average fps, it's fun.]
Alien Rage [average fps, it's fun.]
Enemy Front [average fps, it's fun.]
Judge Dredd: Dredd vs. Death [average fps, it's fun.]
Contract J.A.C.K. [average fps, it's fun.]
Land of the Dead: Road to Fiddler's Green [trashy but it's fun.]
Day of the Zombie [trashy but it's fun.]
SAS: Secure Tomorrow [trashy but it's fun.]
Will Rock [looks fun, i couldn't get it run.]

PS2
Urban Chaos: Riot Response [one of my favorite games.]
Cold Winter [one of my favorite games.]
Area 51 [very good fps]
Darkwatch [very good fps that reminds me of blood.]
Serious Sam: Next Encounter [one of my favorite games and for me the best part of the series.]

XB360
Bodycount [very good fps, it is a spiritual successor to BLACK]
Legendary [trashy but it's fun.]

[Lizzieborden]

Wow, Patho...only game in your list I know is serious sam.
A few games I know and kinda like , but seem not well known:
Nocturne (PC, 1999 ) Music is amazing, too boot. Not really a shooter though
Kingpin (PC, 1999 uses quake 2 engine ). It has a cult following.
Painkiller (PC) not that obscure...

[Dead Reckoner]

Will definitely check some of these out.

Only one that I have to add is Kiss: Psycho Circus. Not a great game but I liked the artstyle and the ability to strategically dismember enemies. Runs on the LithTech engine.

[Lizzieborden]

psycho circus....i'm intrigued!