It's still a bit of a mess, but I got a working build of a game project (not a real game) running on OS X High Sierra with Steam achievements.
I cloned Janet's osx-nick branch and reused the WEG Xcode workspace files (and the Shivah project files). I tried to figure out how to embed a binary version of AGSteam into the app, but I kept getting an error that the library didn't exist in the final executable. So instead I followed the approach that was already partially implemented by WEG (judging by the project files and the lack of an existing port of AGSteam to Mac), and built the AGSteam source directly as part of the project files. Took a bit of knackering about as I've never used Xcode (or even OS X) before, but it definitely is working.
I will try to make a more detailed post of what I did after I try to abstract it out of the WEG files.
I cloned Janet's osx-nick branch and reused the WEG Xcode workspace files (and the Shivah project files). I tried to figure out how to embed a binary version of AGSteam into the app, but I kept getting an error that the library didn't exist in the final executable. So instead I followed the approach that was already partially implemented by WEG (judging by the project files and the lack of an existing port of AGSteam to Mac), and built the AGSteam source directly as part of the project files. Took a bit of knackering about as I've never used Xcode (or even OS X) before, but it definitely is working.
I will try to make a more detailed post of what I did after I try to abstract it out of the WEG files.