I'm sure you know
The Hidden Below?
Chasm was produced by a Ukrainian team, who later moved on to create
Vivisector.
One Russian project that had much hype in late nineties was
Parkan: The Imperial Chronicles, which is a blend of first-person action, simulation and strategy (haven't played it though).
There have been several entirely homebrew Russian 2.5D FPS projects in the vein of
Wolfenstein 3-D, I'm not sure if those were made by the same team/person or different people. These include
Dungeons of Kremlin (probably the most well-known one),
Raising Dead (apparently not the same thing as
Smuta) and
Old Gold (all neatly organized in
this YouTube playlist).
I'm also sure you know about Russian-made
Duke Nukem 3D TC called
Liquidator, which got an independent sequel
Liquidator 2, titled
Liquidator: Welcome to Hell outside Russia.
Kreed also received its share of hype in the 2000's, but turned out to be nothing special.
I guess
S.T.A.L.K.E.R. got enough popularity to be only briefly mentioned.
(BTW, you haven't specified a time frame, so I'm just naming games off the top of my head, in no particular order.)
There was that neat
.kkrieger German project, I wonder what happened to it.
And, on that note,
Cube and
Sauerbraten
I think
Hired Team: Trial was made by some Russian company (Heh, I just Googled it, turns out they made that
Warcraft-y alternate history RTS about Slavs, Aztecs and Mongols (?) duking it out in Medieval times that I've read about in some magazine in late nineties

).
Codename: Outbreak is by the same company as
S.T.A.L.K.E.R., and if I'm correct, it is they who also did a semi-amateur
Warcraft 2000 project (guess you're familiar with it, but if not, it's
Warcraft II with aliens and nukes

).
Psychotoxic was developed by a German studio (I know this gets a bit repetitive but come to think of it, I can't remember any French FPS games, for example).
Mortyr games are by a Polish studio, aren't they?
Neuro was developed by former employees of New Media Generation who had worked on
Hired Team: Trial.
Chrome is by a Polish studio (yay variety!).