Besides the aforementioned Boiling Point: Road to Hell and Chasm: The Rift, I also liked Terminator: SkyNET, Lethal Tender and its sequel Terminal Terror, and the maligned Commandos: Strike Force.
SkyNET had plenty of interesting features including scenes where you could drive a jeep and a Hunter-Killer, but those were separate level set-pieces and not 'drivable' vehicles you could get into and out of at anytime. But it also had some annoying bugs, like taking damage or dying if you walked down any incline steeper than 45 degrees.
Lethal Tender and Terminal Terror were essentially Wolfenstein 3D clones, but they featured mechanics like functional disguises, and non-lethal weapons.
And I had a lot of fun with Commandos: Strike Force's spy character's stealth missions, perhaps because they felt simple compared to something like the Hitman games.

Ah fuck, how could I forget... VIETCONG! I've played it so much, I forgot that it qualifies as an "obscure" game, I guess. It's hands down the best war shooter ever made, I played through it again rather recently (last year, I think) and it remains a masterpiece. It does have its quirks and one or two missions tend to seriously glitch out on ya but the combat and the atmosphere are unlike anything out there and the developers' passion for the setting shows in every detail. Some missions I could play over and over. And dat sneaky anid highly aggressive AI, best shit ever. It's also an absolute blast in multiplayer and it's one of very few titles that I have been able to convince my CS-obsessed buddies to play in LAN. It's so sad that Vietcong 2 was such an utter failure.

Absolutely agree :) The atmosphere is amazing in that game. The only other historic war fps that has matching atmosphere imo is the Brothers in Arms series (at least the first 1 or 2 games).
My favorite mission in Vietcong is the one where you have to defend the hill position with very few men (during a rainstorm I think?). The atmosphere of that mission had me on the edge of my seat the entire time! It really felt like "I don't know where the rest of the squad is on this blasted hill, but I hope they are alive and doing their job. I can't go and check on them because it feels like we can be overrun at any minute, so I can't risk leaving my position." Sort of like Charlie Sheen's character must've felt in the final battle of Platoon: he knows his squad is out there, but he can only hope that they are still alive as he's frantically trying to hold his foxhole.
But that's not even the most atmospheric part. For me it was that nighttime extraction mission where you had to sneak around the jungle at night trying to avoid detection and make it to a lz. With almost no ammo you don't have any other choice but to crouch and crawl all over the place praying not to be detected.

If only there was another game like it :P

Late to the party? Not really. The first Marathon was released one year after Doom, which came out '93 and still it had the better tech, at least in some part. It was one of the first games with a physic engine, I think Ultima Underworld was the first.

As for the gameplay. Well that's of course subjective but I enjoyed them more then I enjoyed doom actually because the story was more interesting, especially the 2nd one. But yeah since Bungie was a Mac only game company back then it had a huge disadvantage over the PC market, especially back in the 90s. They tried to remedy that when when they released it for Windows years later, but then it was too late.

But there is a very decent remake available of all three titles for free. You can download it here.

Oh I remember another one I'm found of, GORE: ULTIMATE SOLDIER

CAPS BECAUSE EMPHASIS.
THE GAME IS LOUD.
REALLY SODDING LOUD.

But seriously, it is another one of those "so bad it is good".

I was quite surprised by a some maps, gun variety and how things got wild at the end.
You start fighting screaming tugs on buildings and streets, and after a while you'll be fighting screaming skellingtons and robots in a virtual world a la Matrix (seriously).

It is really a accomplishment for a small team, graphics aren't that bad either, in fact, there are some really impressive stuff sometimes.

Also, weirdly enough, the campaign was a tacked on thing, or so I've heard, the focus was on building the MP, and the campaign was a afterthought. Which is surprising considering that it is quite chunky, which all afterthought FPS campaigns where like that! :P

This thread is gold. Bookmarked for later use.

That reminds me I have that on CD. Despite the many years i've had it i've only played it once. Didn't seem too bad from what I played of it, (never finished it.) Reminded me alot of Quake.

Yeah I have it on CD and played through it again this year. There's a free expansion pack you can download from the official website (using the Wayback machine) and some patches. But, to get the game running on DOSBox at all, I had to hex edit one of the files. =\ Really makes me appreciate having GOG around, a lot of old games still need tinkering with and it's not as easy as dropping the executable on to DOSBox to play them.

First off, one year is a LOT of time, especially back then. And note that one year after Doom is also two years after Wolfenstein 3D and Ultima Underworld. ID had already well established various standards of the genre, Doom was already a best-selling game, a pop-cultural phenomenon and that one FPS game that everyone had to compare themselves to until the next generation of shooters. When Marathon came out there had already been a flood of "Doom clones" and Marathon is really no exception excluding rather powerful original tech - for a clone, but not necessarily compared to Doom.

As for the physics stuff, Ultima Underworld was already two years old at the time and actually did use its physics in a notable manner - in Marathon I only see the physics engine mess up movement on stairs (and Doom meanwhile utilises velocity and friction to seriously improve the quality of the action but does not use physics to mess with anything else).

Most importantly, however: in terms of mood and setting Marathon had an entirely different competitor - System Shock, also released several months earlier, with even more powerful tech and truly original game design that would pave the way for a different branch of FPS games.

Anyway, I'm not saying that Marathon is a bad game (although I have trouble saying that it's a great one), I'm just saying that even released a year earlier alongside Doom it would have had trouble to "define the genre".

That one was hard to find: Operation Matriarchy

https://www.youtube.com/watch?v=nGpRwrLeYNE

And one of my favorites, but not that rare: Clive Barker´s Jericho

https://www.youtube.com/watch?v=JJKlSIO3E_4

Ok, before I list all of my discoveries here, check this channel out. It´s called Obscure First Person Shooters:

https://www.youtube.com/view_play_list?p=2BBA1AB1CF53EEAC

I have the same list/channel saved, just didn't post because of the "favourite" part. :P

You Are Empty

https://youtu.be/H6I0gCtQfjM

https://www.gog.com/wishlist/games/you_are_empty

El Matador

It's a Max Payne clone (I know it's a third person shooter not an FPS, but I'm counting it anyway).

I've attached a screenshot.

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