What's a Mac? No, seriously though, as far as I know Bryce 5 is OS10 native. Or maybe it was OS9 native? I know it's not really compatible with XP, but it runs anyway. You just can't minimize it the normal way, you have to use the "Start" bar's "Show Desktop" function to minimize it. But as far as I know, Bryce 5 will run on OS10.