Works like magic, thanks! Of course it shows "Application from unidentified developer" at first start (like many apps without Apple certificate, I suppose), so maybe you need to add some kind of instruction to open you game with Ctrl+Right Click and then Open. Or just add a link to this article: https://support.apple.com/guide/mac-help/open-a-mac-app-from-an-unidentified-dev...
Regarding "another FPS" - I feel you, of course. But I think Exolon is more than just walking on straight line and shooting ) I think rocket launcher, shooting color balls, teleports, turrets, exoskeleton suit etc - it all creates Exolon-like atmosphere. Anyways, looking for full version of this game and another games.
Oh, by the way, is it possible to add self shadow? Because it's very hard to pass through ground traps without it.