johnnyturbouk
macrumors 68000
It was removed when OS X went to 64bit only, since mojave. Aspyr was working on a 64-bit upgrade but have given up
support.aspyr.com
Huge shame! I had this on the mac and loved it, i even got the rise of reds, shockwave and contra mods working on the mac natively. Only solution now is windows via boot camp!
*Additional Update for May 20, 2020:
Last year, we announced we would be transitioning to 64-bit apps following Apple’s decision to end support for 32-bit versions upon the roll out of macOS Catalina. Unfortunately, during this process we discovered we won’t be able to update Command and Conquer and have removed it from our store today, May 20, 2020. We will continue to provide customer service support for our customers who purchased this game through us, but have not updated to macOS Catalina. Thank you for your understanding and continued support.

MacOS Catalina, 64-bit, 32-bit, and related Questions
Games Updated to 64-bit The following games have been updated from 32 bit to 64 bit, and are now compatible with MacOS Catalina and up: SimCity 4: Deluxe Edition The Sims 2: Super Collection SimCi...

Huge shame! I had this on the mac and loved it, i even got the rise of reds, shockwave and contra mods working on the mac natively. Only solution now is windows via boot camp!