Since both JR and 25th are run via DOSBox
Same issue here, Mac Catalina. JR runs, but 25th doesn't. The reason...
1. JR runs on Dosbox which DOES work on Catalina now.
2. 25th runs on BOXER (a wrapper for Dosbox), which DOES NOT currently work on Catalina.
Technically, we should be able to grab the game disk from 25th mac app; digging around in the app's contents I see the "Star Trek 25th.boxer" which contains folder "TREKCD" that has all the original DOS game files.
It would be great if someone at GOG would update 25th to use Dosbox instead of BOXER, so that we can install and manage the game through GOG GALAXY. But for the time being, we should be able to grab the game disk and run it through DOSBOX manually.
I was just looking at this trying to figure out why MacOS wasn't listed as a supported OS. It's unfortunate that Boxer doesn't appear to have been maintained at all in the last 5 years. It's unclear to me at a glance if the DOSBox project addressed the core issue preventing Boxer from compiling full 64-bit, but still, Boxer appears to have been abandoned by its maintainer. (It's also unclear to me why DOSBox is still hosted in an SVN repository on Sourceforge, but I digress)
[EDIT: It looks like MaddTheSane forked the repo and is busy at work on it. He's hasn't put out any downloadable releases that I can see though so one would be stuck with building the app themselves.]
I'm still not sure why GOG hasn't already replaced the original Boxer based release with one simply running on DOSBox. At most I think it should only take someone an hour or two. I suppose they could be waiting on ScummVM. Looking at they're commit history, work on their STARTREK engine has been fairly active recently but it doesn't appear that it will be ready very soon.