The 1935 build of S.T.A.L.K.E.R. from 2004, officially released by GSC Game World. Unpack, then run the auto-extractor.
This is a build from 2004 which utilised a completely different physics engine than the one used in the final retail version. This build is fully playable and contains all of the original levels as well as those that were cut such as Dead City, Swamp and Generators. This version is not so much a demo or mod, but more of an insight into the game's development. Curious fans of S.T.A.L.K.E.R. will find this both fascinating and intriguing although may wonder why some elements were removed from the retail release. GSC Game World have issued a disclaimer where they cannot guarantee stability, so bugs and crashes will occur. They have also said that they will not provide technical assistance.
In the zip there is included a file ( profile_vis_fix.rar ) to improve visual quality.
1. Download and extract files to a folder
2. Delete the 'savedgames' folder
3. Run the game with run_alife_s.bat