Pathologic

Well, Black Hawk Down was absolutely awesome for the time. Nowadays they've switched to making the Joint Operations series, basically Delta Force on roids. Even Joint Ops is dated, though, so my suggestion is the new Battlefield series. Delta Force lacked vehicles in the games you played, but since Black Hawk down - and especially in Joint Ops - they started adding more and more vehicles in. Battlefield brings it all together the best, though. I have some issues with BF3 (Origin) so I can't speak for that game, but Bad Company 2 really brought me back to the ol' Delta Force/Joint Ops feel.

I can sort of see where your interests lie. And it doesn't seem like you'd mind going back to some older titles, either.

The Thief series is definitely worth checking out. I never played the third game, but one and two are fantastic. Particularly two.
F.E.A.R. was a fun game, that I somehow managed to finish at 2 a.m. Seems I have some balls, after all. Definitely give it a shot.
Max Payne is a classic, imho. Loved that game when it came out.
S.T.A.L.K.E.R., Shadow of Chernobyl; not a perfect game by any means, but a lot of fun when you get the hang of it.
Risen; a flawed gem, it provides a beautiful open-world to explore, which I think you'll enjoy. Plus there's a sequel coming, so if you like it, you'll have that to look forward to.
Metro 2033, very much along the lines of S.T.A.L.K.E.R., a bit unforgiving, but it has great atmosphere.
Bioshock and Bioshock 2. The first is perhaps better than the second, but both are worthy of a playthrough. The closest to a modern day successor to System Shock as you'll get.
Wolfenstein was very underrated, if you ask me. It doesn't provide deep and engaging story, but it does provide fun gameplay.

I'll assume you've already played Deus Ex: Human Revolution, and Skyrim, but if not, I highly recommend them both.

Hopefully I've mentioned something you've never played, and most of these games you can fetch for a decent price online.

damn i knew this would happen... i know all games reccomended!
a few i have beemn reminded about though-
deus ex mods, i am yet to try ANY. probably cos i cant accept any altered version of the game itself. but really should.
ultima underworld. this i have to play, and really dont know why i have not since i love the design of LGS games.
stalker- i have this but my crappy laptop wont allow me to play it! besides ive heard it lacks depth compared to LGS/ion storm design but is still worth a shot, so maybe ill upgrade 1 day.
and papafern....ill be a man and admit that pokemon is [censored] AWESOME! at least it was when i was ten years old. it makes me laugh that its a kids game yet it has more depth than most advlt games today....

oh i forgot thanks for the replies

Borderlands, Beths Rage, the old: Black Isle Fallouts, Planescape Torment, Baldurs gate ( all have great mods now, check out GoG's mod guide for Torment http://www.gog.com/en/news/mod_spotlight_planescape_torment_mods_guide/.

Hmm Two worlds and Two worlds two, fun to play but honestly bad in lots of ways such as dialogue.
Dark Messiah Might and Magic looks fun, but yet to play.
Fable three is silly but the little played is fun.
Shooter Warhammer 40,000 space marine is one on offer on steam atm. Can't say if it's good, but cheap for now and reviews have said for a plain no frills shooter it has some decent features.

One a guy I know on a TeS fan site has recommended Ventetica

STALKER is a good series of games.
The Mafia series is really good as well, I'll highly recommend it.

http://youtu.be/hwOYJ2ctPsQ

Metro 2033 is one of the most atmospheric and moving games I've ever played. The game is terribly underrated, and though it's not very long or deep by RPG standards, the depth and gunplay more than makes up for that.

There is a genre for these special games. I also heard the genre is dead in the eyes of most developers.

I add these two:
The Chronicles of Riddike: Escape from Butcher Bay
Minecraft

Portal? I played Portal 2 during New Year's night. It has unique gameplay. It's like a first person puzzle game and using the portals is really cool because you look in one and see what's out the other. It's almost like having mirrors in games except they're not reflected.

Goodness yes to portal. A puzzle with story and writing humour to match many rpg's.. Play that at least once.