The Macintosh was supposed to be low-cost.
A 68000 CPU could be used with all 16-bit components but the Lisa was using 24-bit and 32-bit components (for reasons) making it expensive. In 1979 a prototype Mac board used a 6809 CPU because Apple wanted a system that could calculate in 16-bit.
The original Macintosh project overlapped development of the Apple Lisa. dmg file most likely means the game is for OS X.
smi file most likely means the game is for OS Classic.Ī.