What's your favorite FPS game that many people don't know about?

The best FPS ever was Call of Juarez Gunslinger for me but don't know if you can call it less known game :)

Call of Cthulhu: Dark Corners of the Earth.
Highly underrated game.

Oddworld: Stranger's Wrath

Blockstorm (ok, I'm sure a lot of people here have heard of it or even own it, but I'm betting few play it). It's actually the only multiplayer-FPS I like. The ability to add/remove/shoot/explode maps' blocks adds a lot, in my opinion. Also, ranking in the top 10 in any game mode for the week earns you a free IndieGala bundle, so that's a plus.

Vietcong

UT99. I guess many people do know about it, but most here were probably born after it was released so probably never bothered to play it. They should. It's amazingly good to this day.

hmm Don't think I have played any small indie FPS yet so have no answer to this

Natural Selection 1 :(

007 Goldeneye on N64, memories <3

Good old Wolfenstein Enemy Territory

Hard Reset?

Conflict Desert Storm could switch between FPS and 3rd person and I did like it.

F.E.A.R seems to be a bit forgotteh now a days and it is probably THE best FPS i ever played. 2 and 3 where a bit weaker but fun for a playtrough or 2 aswell.

Singularity as mentioned before was far better than i expected and well worth it!

Wolfenstein enemy territory.. If this game came out on steam and you could find servers that weren't filled with bots i would so play the shit out of it again..

S-T-A-L-K-E-R call of pripyat and shadows of chenobyl. Havent tried the second one yet.

Edit: Also a shout out to Azure sheep mod for Half life blue shift.. The mod that was how blue shift should have been and even one of my all time fav mods!

Since this is about a FPS that many people don't know about... I can tell two

TimeShift
DarkSector (yes, isn't FPS, but shhh, don't tell to anyone)
America's Army (but not that horrible version 3, but the amazing V2)

I could say Singularity as well, but a lot of users said

My favorite is a free one, for win/mac/linux: Cube 2: Sauerbraten

Serious Sam

Now that u mention serious sam,it was like the best known game in that time.Popular too.

Still,i do remember one gem from that era,following the same gameplay style like the popular SS.
It was the Will Rock game.

Doom2 in Kummeli version (which will not say anything to anyone unless you are Finnish or really strange or preferably both).

/jk. or not.

The Darkness 2

I really liked Singularity. ;)

Outlaws. It seems quite popular, but there are a lot of people that have never heard of it. It had a demo before release (that was common back then). I liked it and bought it at release. I loved it, but couldn't get any of my friends interested. We had regular LAN parties since this was before high speed internet was common, and wanted to do some multiplayer with it, but they wouldn't give it a chance.

Mine would be XIII. Anyone remember that?

Red Orchestra 2
Rising Storm
Rising Storm 2: Vietnam

Murder Miners. Not a lot of people play it, but it is a ton of fun to play as a casual FPS shooter.

Black(ps2)