I guess you're missing the file "gfx.wad"
Oh shit forgot to mention, you can get the pistol before by killing barney under the falling computer thing. It's pretty hard to get barney under it but it works and you can have the pistol before the crowbar.
I don't think it would work because in the beginning of Residue Processing but it would be co0l ????
https://drive.google.com/file/d/0B1J0OvNuuZf8b1VJV1VDajhrUGM/view
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