Sadly, I have had to update the pages for my Mac OS X games to show that they no longer work after Mac OS X 10.14 “Mojave”. This is because Apple removed support for 32-bit programs from OS X 10.15 “Catalina”, released late 2019. (An event affectionately referred to as the App-ocalypse.)
I may try to rebuild the Unity games at some point. I already started improving Pawns for iOS, which gives me a head start on a new Mac version. I’m not sure how difficult A Tack! will be to update.
Amazingly, the three non-Unity games (Black Cube, Asteroid Rally, and WordBeGone) have been working since the earliest versions of OS X. I recompiled them for the Intel transition about 10 years ago, but that was all they needed. But there is no simple way to rebuild them now, and I have no plans to rewrite them.
Ironically, my oldest “Mac Classic” games (3d Brick Bash! and 3d Paddle Bash!) CAN be run on 10.15 using an emulator like SheepShaver.