I managed to get the Mac version working with a simple addition.
Right click and use "Show Package Contents".
Navigate to Contents -> Resources -> app.nw
I introduced a package.json file here with the following contents:
JavaScript:
{
"name": "",
"main": "index.html",
"js-flags": "--expose-gc",
"window": {
"title": "",
"toolbar": false,
"width": 816,
"height": 624,
"icon": "./icon.png"
}
}
Now, double-clicking on Game.app works.
Besides the "index.html" entry, everything else is copy-pasted from another Mac game. I didn't bother changing those entries.
Credit to ChatGPT for giving me pointers in this direction.