It'll probably be neither. My guess is that they are using Sierra's own adventure game interpreter (AGI) software, which is the reason for the very low-end minimum requirements.

In recent years, people have figured out and reverse-engineered the language and tools Sierra used to create their graphical adventure game. Theoretically, if you can find a commercial Sierra interpreter that will run the game on your platform, you can do so.

Some people have also written their own interpreters that will run under Linux and some may even be ported to Darwin/Mac OS X.

But, theoretically, you can take the game data files, and run them with the Apple IIgs Sierra interpreter, or the Mac version (which will only run under System 6.0.7, and may or may not be in color), or the PC version, or the Amiga version, or the... you get the picture.

But, with such low requirements, Virtual PC will have absolutely *NO* trouble playing the game. I have played those old Sierra games under Virtual PC and they play just fine.