I have found some amazing stuff in a Mega upload archive. This is a large archive of Stalker development artwork and images that were drawn during the development of the maps in the Stalker series of games. These development sketches give an insight into the work process when developing a new map in the Stalker SDK. Plus there are images of cut mutants such as the Morlock, which looks too much like a Warhammer 40K orc. Here are a few more images from this archive.
https://securitronlinux.com/stalker-builds-design-artwork/images/.
There are many sketches of maps such as Jupiter, Zaton and Jupiter Underground. Jupiter Underground changed a fair bit since the early builds, but it is still a very good underground map. Very challenging in mods like OP 2.1, it is full of all kinds of horrors. Such as strange legless creatures that fire energy bolts at you. That is quite a challenge to get through, you need all collector stash artifacts, such as jump artifacts, and then you can get all the way up the high walkways around the central round hub area. This area is perfect for sniping monsters from a safe(er) high position unless the enemies have an RPG or a VOG 25 grenade launcher.
It is amazing if a fan of the Stalker games can find such a fascinating archive of files. I have uploaded a large amount of Stalker dev documentation here: https://drive.google.com/drive/folders/17GwRB4sleJXZ5Y2pRGvSjtxVqHEA7CR9?usp=sharing. This should be very interesting to peruse and learn about the Stalker development process. The rest of the content is in this Mega archive I mentioned. https://mega.nz/file/ppxESI6T#sJaSjCzDyuxSO6pZU18Jbi3Y4_6O63zV-MLlYFsz3As.
There is also this archive, which has a massive collection of Stalker build screenshots from just about all builds of Stalker Shadow of Chernobyl during development.
https://mega.nz/file/EkoGRCbC#8oVcoN9lGH45y6iPie-3NLizt_rgs4h5Ujo0O9TOxyA.