Oh, to be a Mac owner. Not that we've got it great on PC - my rig's been bricking it since last week's Windows update, after all - but it's been a long time since a big OS update killed half of my game library. Desktop gaming always gets around to leaving a generation behind, though. 32-bit applications have been on the chopping block for a few years - and with this month's "Catalina" update, Apple are making the first move towards killing them off for good.
It's hard to get a good of how widespread this problem could be. Whether a game is 32- or 64-bit is the kind of finicky tech detail that gets left off the box cover. That cut-off does, however, include the bulk of Unity games created with Unity 5.5 or earlier, and many bigger games from up to the early 2010s. It's normal for older games to be trickier to run on modern hardware, but this bar could cut off hundreds of games across the last two decades.
Mac porting house Aspyr have put together a list of their own 32-bit titles threatened by the update. Those games were all removed from sale three months ago, though they should still hang about in your Steam or App Store catalogue if you'd already purchased them.
It might not simply be a matter of just updating a game to 64-bit, either. Besides obvious issues like developers disbanding, losing code or lacking resources, creator Paolo Pedercini notes that Mac's "Gatekeeper" may end up blocking updated apps that aren't "signed and notarized by certified developers".
It turns out the Indiepocalypse is not going to be triggered by too many people making cool games but by my old dude C̸͕̕Ä̵̝́P̴̣̓I̴̊ͅT̷̠̈́A̷̼͂L̷̖͂I̶̧̛S̷̮͆M̸̪̀
— Paolo Pedercini (@molleindustria) September 3, 2019
The update will also mess with a handful of older file formats and kill off apps, far beyond games. That's the inevitable march of time for you.