Having only ever owned one Apple product, the original iPad, I’ll let this succinct quote from Kotaku sum up the situation.
“iOS 11 is currently in beta, but even now, some 32-bit games aren’t showing up in the App Store. You can still search for them on Touch Arcade, and as Gizmodo’s Rhett Jones points out, ‘If you use a direct link, the app is still available for download. What this means is you can still grab that old app that you meant to buy or would like to own again.’ That method will only work for a little bit longer, though; in the coming months, iOS 11 will drop support for 32-bit games completely.”
The rest of the post has a few quotes from iOS developers about their individual titles but this is the gist of it from 9to5Mac. “Starting in January 2018, all new apps submitted to the Mac App Store must support 64-bit. From June 2018, the same requirement applies to new apps and updates. This marks the start of a transition where in a few years, 32-bit Mac apps will no longer be supported and won’t run.”
This stands to impact tens of thousands of apps and games from defunct studios or from teams with limited resources to make the required updates. If you’d like to verify which of your own apps might be at risk, 9to5Mac’s post has a handy walkthrough. Otherwise, try Touch Arcade to get a direct link to download some of these endangered titles.