I've downloaded the "Call of Chernobyl" stand alone mod (that still requires Call of Pripyat to be installed even though it doesn't actually modify it.) and I've found myself always coming back to play it regularly more than any other game. If you don't know it's basically a mod that uses the C.O.P. engine and has ALL the levels from all Stalker games. You can play as any faction and go anywhere. Back in 2008-2010 I was pretty obsessed with the original Stalker games and loved the atmosphere, but of course moved on to other things. Before this I did try the Lost Alpha but found that the levels were missing lots of buildings and interiors that I liked.
This mod has got me hooked. I could be playing anything else but I love booting up C.O.C. just to go artifact hunting and exploring. The only thing that bugs me is that enemies are bullet sponges and will often take a full clip to put down unless you make a head-shot. I will sometimes just enjoy sightseeing and listening to the ambient music. The setting may be "negative" with the aftermath of ecological disaster and horrific mutants but at the same time it's beautiful and pleasing. It's strange.

I guess one thing I like about the Stalker games (and older games in general) is that you're always in full control. Modern games seem to be too scripted and sort of "force" the player to have a certain experience. They spoon feed you , beat you over the head and then pull you along on a rope and then grab your head and force you to look at what they want you to see.

Didn't know about this mod. Thyanks!

The bullet sponge thing almost made me give up on the S.T.A.L.K.E.R. games until I found the advice to raise the difficulty level to combat that. After that the games became a lot more enjoyable for me.

Would those of you familiar with that mod say that there is no need for the first two games at all (though I do have them all) if one has the last game and that mod installed?

If you missed the recent news on it, they just released and updates directors cut version on moddb for lost alpha:
http://www.moddb.com/mods/lost-alpha/news/stalker-lost-alpha-developers-cut
Might have sorted some bits out.

Thanks for the suggestion. now I had to put S.T.A.L.K.E.R: Call of Pripyat onto my wishlist, just so I could try this mod.

I wasn't aware of this mod either...thanks for posting this! Do you know if this works well on Win10?

I play it on a new Win10 system with a Geforce 1070,.. and also an older Win7 gaming laptop with a Geforce 660M. Runs fine on both. I thought that the difficulty settings in Stalker only affected the amount of damage done to the player only and that the only way to make the enemies take fewer bullets was to use a mod.

The mod only requires Call of Pripyat to be installed.

They affect AI chance to hit player.

Call of Chernobyl does not require any Stalker game, its a standalone mod, based upon released Xray source code. However, because it includes few resources from original Stalker (like leftovers of maps and textures), you (legally and consciously) should invest in license.

... there is also Call of Misery, for those, fans of BDSM... FYI... YMV :) Have you checked this? In case you had, having a mod, mod a mod, is not that bad. :)