For a game that's open source and written in JavaScript, it's a shame that the packaged, downloadable version is only available through Steam on Windows. I'd pay the $5 for a DRM-free Mac version.
It's also available for Linux. If the developer doesn't already own a Mac and have a paid Apple developer account they are probably not going to make back their money buying those things in order to make a Mac build.
The latest (as of this comment) change to package.json was a PR to turn on macOS builds: https://github.com/tobspr/shapez.io/pull/687 but unknown if the reservation was more political than technical
There are a few sites that show step by step how you can run Mac on a VMWare on a PC. Yes it disregards some T&Cs but the dev will avoid the $1000 apple-tax.