I made a tower defense that runs on any real address. Type a street, defend it.
You type in an address, the game streams Google's photorealistic 3D tiles for that place, and the enemies come up the actual streets from OpenStreetMap. Paris, Tokyo, New York, or your own street.
Towers, a tech tree, upgrades, a hero, abilities like nukes and an orbital laser, and you can jump into any tower and aim yourself. Co-op works in the desktop app.
It's free and open source. Play in the browser or grab the app for Windows/Linux: https://3dtd.sgeht.net
More videos on Youtube here: https://www.youtube.com/watch?v=Eq5YEDuE3x8
One catch: you need your own free Cesium Ion token for the map tiles, since they're billed per request. The game walks you through it.
Happy to hear what breaks or where it's too hard.