There is a game I played once that I am trying to track down, but I can't recall what it was called.
I'm hoping if I can describe it adequately someone might recognize it.

The game was a first person shooter.  I believe I played it on a PC.  It had a modern setting in an urban environment.  (Or at least nearly modern; it wouldn't surprise me if it actually took place in the future, but it wasn't "space future on an alien world," you played in a modern-looking urban city.)

Visually the game looked rather old or low-poly, like it might have been built with the Quake 2 engine.  I can't recall distinctly though, so I wouldn't exclude anything that looks like it could run on a PS2.  But I'm pretty sure you could see things like street lamps and guard rails with distinct polygon edges instead looking relatively round.  I'm quite sure this was before normal maps were used in games.

What I recall most distinctly about it was that it had a surprisingly high amount of audio clips.  At least, compared to what I expected given it's visuals.  I think there were two character models for the thugs you were fighting, which is kind of what you would expect for a game of that era, but I could play through the level twice and still hear new voice clips from them.

I think in the first level you were on the ground level, and then the second level you were on the tops of some skyscrapers.
I think the levels I played were pretty linear, but I also recall there was at least one point in the first level where you could take a different path by cutting through a building, although it connected back with the main path.

And finally, although I could be completely wrong about this, I have this vague feeling that the game was released for free, like the guys who made it decided to release it for free on its five or ten year anniversary.  Mostly I think it was released for free because I can't quite imagine how else I was playing it, because I would have remembered if I payed money for it, and I just don't think it was a demo.  But I could be wrong, so don't hold me to that.

I know this isn't much detail to go on, but I'm hoping it's enough to jog someone's memory.  There can't have been too many shooters from that era that opened in a modern city.

(And no, it wasn't Sin.  I am familiar with that game.)

Kingpin? 

Kingpin:
That certainly hits all the marks I described, but that's not the game I was thinking of.
If not for the excessive foul language, I think I would love to play that game.

Riddick:
I can't find any videos of that that look old enough to be what I was thinking of.

Urban Chaos:
Wow, that game looks classic!  But no, that's not it either.

COD/MOH:
I am absolutely certain it wasn't any historical war game.  Unless one of those games did something more modern and fictional prior to the release of Modern Warfare, I would write off those games.

5 hours ago, OandO said:

Solider of Fortune?

I'd forgotten about that one.  I remember playing that one back in the day.  Man I gotta find a copy of it again.

But no, that's not the game I'm trying to think of.  Certainly fits the description I gave, but not the one I was thinking of.

I'm starting to wonder if this was something particularly obscure, like they tried to self-publish it on the internet way back before there was Steam or anything, which is why no one has heard of it.  Or maybe it was a mod or a TC some group made.  (But I doubt its a mod, I don't play enough mods to have forgotten one as extensive as that would have to have been.)

It's probably way to well-known to be the right answer to this question, but Deus Ex 1 seems to fit this bill fairly well.

On a side note, someone needs to make a bot that can find the names of games and movies based only on half-remembered descriptions. Trivially, you could train a classifier based on descriptions after which the author successfully discovers the identity of what they were describing. Human memory is very strange, but I can't imagine that there aren't also a lot of patterns in which sort of details players are likely to remember/describe, etc. or even which elements are likely to be remembered incorrectly.

Ah! I think I found it!
...Mostly.

The game it appears to be is "Gore: Ultimate Soldier"  Or rather, "Gore: Special Edition" which was release as Free-to-Play some years back as a free and updated version of the original.

Just about everything connects right.  I remember the same few thugs that repeated as your many enemies, especially that big guy wearing orange and a vest.
The first level is actually a training level, so if we ignore that, then the next level is the one I described as the the first level, and the third is the second level where you were on tops of skyscrapers.  That level in particular is what I remember of the "second level," and when I dug through my old PC I found that's the level where my last save file was.

There's only one thing that still bugs me.
The "first level" (actually the second) is NOT what I was remembering; what I was thinking of.
This would be easy to write off as just a detail I had wrong, but this really bugs me because that level I see in my head is what got me thinking about this in the first place.  A couple weeks back I was thinking of settings for FPS games, and when I thought of modern-ish settings, this particular level popped into my head.  And I wanted to go back and revisit it.

But when I looked it up in YouTube videos, and when I played it again just now, everything fell into place except for that one level whose memory sparked the entire motivation to revisit this old game.

This leaves me in a state that I don't think anyone can help me.  What was the level I was thinking of?  Did I actually grab that from another memory of playing another game?  Did my mind just warp it somehow into something completely different?  Was there a secret alternate version that I had somehow unlocked when I first played it, but didn't when playing it just now?  (That's actually a neat idea, actually.)  Or was there some update where they revised that level?  (The one I see in my mind's eye was in fact a less well-designed level.)

I don't know how I could share what I see in my mind apart from drawing some intricate detailed picture, which quite honestly I don't think would be worth my time.

Here's a super quick drawing though.

I remember this part where I was running around outside between buildings.  There was one segment where you just around this one building (purple path) but you could alternatively go around the other side and then through the building (raspberry dotted path.)  Through the building wasn't very intricate, I think it was just a path through a hallway.  The reason I remember this one segment is because when I got to where the two paths meet, I noticed I could go through the building, and when I did I found that it just led me back to where I was, so I guess I went backwards through an alternate path.

It's not much, but beyond that I'd have to draw out detailed pictures.  I remember there being a vending machine, a light post, some grass...  really generic stuff.

But like I said, everything is definitely Gore.  The thugs, the setting, and the level after this one, all totally that game.

Well, thank you all for the help!
 

8 hours ago, cowsarenotevil said:

It's probably way to well-known to be the right answer to this question, but Deus Ex 1 seems to fit this bill fairly well.

On a side note, someone needs to make a bot that can find the names of games and movies based only on half-remembered descriptions. Trivially, you could train a classifier based on descriptions after which the author successfully discovers the identity of what they were describing. Human memory is very strange, but I can't imagine that there aren't also a lot of patterns in which sort of details players are likely to remember/describe, etc. or even which elements are likely to be remembered incorrectly.

Heh, I remember once seeing some site that would guess what TV show or movie you were thinking of.  It would just ask you a series of yes or no questions to narrow down what it could be.  It would first just ask if you were thinking of a movie or a TV show.  The next question for the TV show was "Does it take place in a city?"
It was actually a user-updated database.  If if failed to guess the one you were thinking of, you were supposed to add your own question that would separate the show it guessed and the one you were thinking of.

You could adapt that same process to video games, and/or adapt it to help people find a given game too, I suppose.

Those two are like my two most favorite shooters of all time.