The local variable names look like the code was decompiled with ILSpy. All the magic numbers probably (hopefully?) were constants in the original code. The crazy indentation looks like the decompiler just doesn't use "else if". The goto's were just old ILSpy versions being bad at control flow reconstruction.

But neither the C# compiler nor the ILSpy decompiler moves code to different methods/classes (only the JIT does stuff like inlining), so yes it's really a single enormous class handling every possible item in the game via cascading if statements.

Yes it's decompiled, so the chains of if statements would likely be switches instead, but basic things like an object having thousands of properties are exactly as the programmer wrote it.

I have to believe there is a 0 percent chance a human wrote all of that. It's the only thing that will keep me sane 8)