Topic. Press Start, choose the difficulty and boom!... black screen loop. Dev, fix this Mac version!

[TEMPORARY FIX]
I was in talks with the dev and turns out that "libGalaxy64.dylib" file was missing from "Contents/Frameworks/MonoEmbedRuntime/osx/" location.

Just paste it to osx folder, you can download it here: https://drive.google.com/file/d/123a9x8jopI5jVcYsB0msOfgXiLEbxD4W/view?usp=sharing

Once you do that, just go back to Galaxy and press Play and game will be ready to play :)

Guess they will officially fix that in a future update, so stay tuned ;)