You might be right about GetAsyncKeyState not running on a Mac or Linux. I haven't actually tested it. I think I figured it'd run regardless of which system because, hey, it's just PowerPoint we're talking about here.
Definitely something else. Unless I need some more VBA experience to put on my resume (which is why I made this particular game in the first place), I don't see any reason to go back to PowerPoint for my game making needs.