Oh and for all of GOG's Unreal games just pick up a copy of the Unreal Anthology instead. All DRM-free (aside from serial where needed) and usually cheaper than just one of the games on GOG.
Yeah, my CD drive didn't seem to like DOS much so it was only with GOG's release that I found out about that. Quake was the game that made me sort that thing out.

sok - so blood is the way to go?

These.

Also, Rise of The Triad and Blake Stone if you're into sprite based shooters. Painkiller and Blake Stone are my personal favorites on this site.

Also theres Unreal Tournament 2004, which is great fun.

Giants: Citizen Kabuto might actually be the best single player shooter on GOG. It's a TPS, but has a very PC feel (perspective can also be changed to first person). The jetpack is pure joy and the game can be pretty funny as well.

I like Shogo but it's mechanics are awful. Critical hits in an FPS reward spam over accuracy. Also, whoever starts shooting first tends to win. Bot ai is pretty bad (totally unaware one minute, super sniper the next). There's no facility to rebind keys in game (really frustrating for the scoped rifle whose key '5', you have to toggle to get scope). What Shogo does have is a lot of personality. A game made by a bunch of western anime fans making the mecha fps we'd otherwise never get. It's intro is one my favorites.

I wanted to like Chaser but I couldn't get into it with a couple hours effort. :( Too many hitscan weapons and uninteresting bots.

Duke 3D and Blood are classics, Blood 2 is awful (broken/ unfinished), Unreal is overrated, Unreal 2 is awful (you handle like a tank), Serious Sam and Painkiller define the 'arena' subgenre of fps (I like them).

If you're looking for a single player FPS then it's either that or Painkiller that would be my number one recommendation.
Shit! I completely forgot that Serious Sam was on GOG! Yeah, that's another contender for the throne, Oslin.

Sorry but FarCry takes the cake

No, first half of Far Cry might arguably take the cake. But the second half of that game was quite horrible.

so blood it will be! not too much of a fan oof games likesserious sam and "mindless" games over all - if they are not true cult classics like blood. far cry seems like a aged version of crysis. will have to save shogo and unreal for later perhaps. thanks for advice!!!

I'm not an FPS expert at all.

I'l just throw a couple of names, maybe someone else can enlighten.

Arma and Tom Clancy's series for something more 'tactical' and 'realistic'.

What about XIII? I love the visual style, but I don't know anything about the actual gameplay.

It's an ... Interesting combination of stealth gameplay and shooter. But visual style is pretty much all that's great about it, actual gameplay is just slightly above average.

Yeah, shame really. It got off to a good start too. I liked the challenge.
The Crysis games are much better. So is Far Cry 2, even in spite of its enemy spamming and general lack of relevance to the first game. .

I played XIII on the Gamecube years ago and thought it was pretty interesting. The actual shooting is fairly by-the-numbers but the art style in unique and the story is quite good for an FPS.

Edit: Also, Adam West is your commanding officer. That's a big plus, in my mind.

Personally i like judge dredd

People say its horrible, Im unsure why, It has its faults but compared to today's generic shooters, This is golden IMO

No-one mentioned Realms of the Haunting?
Sure it has more going on with strong puzzle solving elements but you do shoot things with an actual gun in actual FP perspective!
You also have a gun in Outcast...

Son of a duck, that's spooky.