Checked most of the versions from the SteamDB of the KF and got some info: versions above 2013 has a problem with invisible units, version since 2016 has a problem with the ui and invisible units, I went to idea about to try re-check every single version of Killing floor to find a correct one. By screenshots I saw, there was a guy 100% game on January 2014, other dude with a single achievement got it in October the 10, 2012 (if i remember correctly) so might the problem not in the KF files but in the DA2 f...

This bug makes the game impossible to play! 1) All the specimen are invisible to me; 2) They don't take any damage to me, so I get stuck and surrounded by invisible Specimen; 3) I can kill them but I only see blood floating when I hit them; Please Help I love this mod and I can't find a solution to it!!!!...

Case closed.

Game loads fine but once I make all my selections & start the game the enemies are invisable! I can see them on my radar, my guys are firing at something but I don't see any enemies!

If anyone is interested, I will tell you how I got it to work. Also, I will give credit to Li Deatus for his guide. http://gtm.you1.cn/sharedfiles/filedetails/?id=1225250030 Update 07.10.2020 : This method is no longer an option. So please read comments #7 and #8....