This is the 1993 SimCity 2000, running as a DOS program in an emulator, as a lot of GOG programs do. I was expecting a rewritten Mac OS X version of it (I used to run it in Mac OS 7.5 I believe), but it runs fine. The graphics are a bit crude-looking, but that's how it looked in DOS (it seemed to look better under the Mac OS.)
Note: this is now $5.99, not $2.99 as I expected. I paid anyway as SimCity 4 won't run under 10.8 (or probably 10.7 for that matter.)