You are probably missing your gameinfo.txt file, it happens to me a lot. I am running Windows 10. What you can do is delete your local game content and reinstall it. Believe me, it sucks to have this frequently. Especially because I am a SPY MAIN! Gotta keep trickstabs on par u know? :) Hope this helps, if it doesn't try finding out what the gameinfo.txt has inside it and make your own in the correct file path, (srry idk what it is)

~Tech22

P.S. Srry for wordy answers