I just found out from Apple's downloads page that the Tomb Raider Anniversary edition "requires a Mac with an Intel processor".
Apple bundled the original game with Macs back in 2001. Given that many Mac users may have upgraded to later Power PCs, but haven't yet migrated to Intel Macs, it seems a bit unfair that there's an assumption that all players of the original game must have moved to Intel by now.
Let's hope that companies like Blizzard continue to keep the Power PC door open for another while.
