hi, 
 
i've just bought stalker (SoC) from the steam sale, and i wonder if i should play it with mods or just "clean" stalker?  
and if with-mods, which mod?

for example i looked at the complete mod, which says some nice things on this page http://www.moddb.com/mods/stalker-complete-2009 , 
but some of the improvements, like "teleport", "anti-radiation injection system"... i'm worried that perhaps 
they change the game a little too much...

Complete 2009 is a must. Realistic Weapons optional but I think it changes it for the better.
 
Lurk if you like stealth gameplay, it lets you kill human enemies without alerting everyone nearby.

Agreed. Start fresh with Complete only. Think of it as a fan patch.

Yes -- the complete mod is a must! Changed the whole game for the better. SoC is a great game without Complete '09, mind you. But in my experience, after having played with the mod I could never return to regular vanilla version.

Damn, I started the original game back on release without any of these. Reading through the list, I can imagine it providing a far better experience.  
 
Good thing I downloaded the STALKER Bundle yesterday :)

Should I play it with the 2009 mod or the 2012?

Can you use the complete mod with Call of Pripyat?

I'd definitely recommend playing it with the mod as well. 

" Should I play it with the 2009 mod or the 2012? "

" Can you use the complete mod with Call of Pripyat? "

Thanks for pointing out this mod! I never remember to check which games have mods. I've been meaning to get into STALKER and this looks like a great way to do so.

Is this available to all three Stalker games? I am going to start with number one of course and work my way through.  
 
Also, why is Clear Sky never on sale? It looks great,

" Is this available to all three Stalker games? I am going to start with number one of course and work my way through.   Also, why is Clear Sky never on sale? It looks great, "

" Is this available to all three Stalker games? I am going to start with number one of course and work my way through.   Also, why is Clear Sky never on sale? It looks great, "

So what exactly do I download to play Shadow of Chernobyl? 

" So what exactly do I download to play Shadow of Chernobyl?  "

Yes there is a separate mod for each of the 3 Stalker games, here's the official page: 
 
http://artistpavel.blogspot.com/search/label/stalker  
 
I've only done SoC so far, but I'd imagine the instructions will be similar on the other two: 
 
install the game 
patch it with the latest patch 
run the game at least once 
run the setup.exe you downloaded with Complete 
start a new game
 
I followed those steps exactly and it's running like a dream.  I never did finish Clear Sky for whatever reason and I have yet to buy Pripyat, but I can say that the original STALKER: Shadow of Chernobyl was great and I'm kind of excited to jump back into The Zone. 
 
STALKER games, for those of you that haven't played them, are what I like to call 'weird Russian games'.  They're a different flavor of game than what you're used to and they're kinda buggy honestly and that may put some people off, but I love the creepy ass world they've created
 
Granted I did just get a new GTX 580 last week  =)