Apple released macOS Catalina on October 7th. This version of macOS is not compatible with 32-bit apps. The Infinity games are all 32-bit apps.
I began a port of the Infinity games to a new tool-chain that supports 64-bit apps in mid-summer, once it became clear the existing tool-chain would not support 64-bit apps and therefore macOS Catalina.
For Mac users, if you upgrade to Catalina now the Infinity games will not work on your Mac until the port is completed, unless you install a virtual machine and then run an older version of macOS on it. (You can also revert back to Mojave if desired. An example of how to revert from Catalina is here. You can also use your Boot Camp Assistant and then install Windows for free while also having Catalina installed, here.)
The port is well underway. The game engine has been ported and the code for working with campaigns has been ported. The user-interface work has begun. Almost all work is now focused on the port.
My best guess is that the port will be completed in January. I will post updates once I have a better idea of when the port will be completed.
Once the port is completed, Windows and Mac releases of Infinity games will move to the new tool-chain. There will then probably also be iPad and Android tablet versions released at some point after that.