Hi folks!
I was able to open the game on MacOS with a little big of fiddling, and I figured it would be a good idea share how I did it! The instructions here are based somewhat on the instructions from this forum post:
https://answers.unity.com/questions/1377896/the-application-cant-be-opened-mac-b..
Step 1 - Copy all of your files to your home directory, or a folder inside that directory
I'm not sure if this step is 100% necessary, but I've run into some weird permission issues when trying to open from the Downloads or Desktop folders, so this is more of a "better safe than sorry" thing.
Step 2 - navigate to the folder where the Game.app file is in the terminal
For these next couple steps, you're going to need to use the terminal. If you're not familiar with it, it can be a little intimidating, but bear with me! I'll walk you through this part!
You can open the terminal application in MacOS by pressing Command+Space and searching for Terminal
Once that's open you can navigate to the folder by running this command:
cd ~/path/to/file
cd stands for "Change Directory". For my setup with Escaped Chasm, I would run:
cd ~/Games/Dwellers\ Empty\ Path/
You can confirm you're in the right folder by running ls and seeing if Game.app is listed
Step 3 - Run chmod
Once you're in the folder with the file, run the following command:
chmod a+x Game.app/**/*
Essentially what we're doing here is adding an "executable permission to all the files under Game.app. chmod stands for "Change Mode", and a+x means "add the executable" permission.
Step 4 - Open the Game
There's one more small step here. Once again, navigate to the file in the finder and RIGHT CLICK on Game.app. You should get some sort of dialogue that says something along the lines of "MacOS cannot verify the developer of 'Game.app'". If you right-clicked though, there should be an "Open" button at the bottom of that dialogue. Click "Open" and the game should run!
You should only need to perform these steps once. After that you should jut be able to open it every time.
Let me know if this was helpful or if you ran into any issues!