When trying to run the code (with fixes), I ran into an issue. As you might know, I am running Linux. Well, thankfully, Mono on Linux can load managed libraries built in Windows just fine. However, what it can't do is run native (C/C++) libraries built for Windows, and sadly Unity has one of those.
Without access to the code, I can't know for sure, but according to the stack trace, Game's static initializer (or static constructor in C# terms) does try to initialize some of the Unity stuff. The managed Unity stuff then tries to call the native Unity stuff, which of course does not work in Linux, and I get an exception indicating it cannot find a method it needs.
Sigh, I guess I will have to setup an IDE in Wine and try again there.