Not my game, but the creator https://x.com/colin_d_m?lang=en posted a lot of tweets with technical details, also his website I think has some info.

He had some pretty interesting methods for 3D building transparency and stuff like that

He looks like he had a lot of fun with that. 3D maps like Google Maps/Mapbox/Maplibre can more or less serve as your engine if you have a game in mind.

(It’s pure TS/JS with Electron, in case you don’t have Twitter account)