Paul, I did not parse C++ but rather C#, a bit easier

Since the whole API was in C++, to use it from pascal it was necessary to make another dll that wrapped the C++ calls with C.
So I searched and one guy did a dll like that already, and provided C# bindings for it:
https://github.com/rlabrecque/Steamworks.NET

I wrote a mini parser that just extracts the functions, enums and structs (and comments too when possible). Maybe later I'll add it to the rep, in case someone is interested on it.