I'm not sure but I think it's a false positive. My virus scanner flagged the file "Assembly-CSharp-fistpass.dll" as a trojan and removed it. The game won't run properly without that file. The solution is to reinstall the game and white list it in your virus scanner app.
It is safe or is it a trojan? Can't say, I'm not a security person. So white list the app at your own discretion.