You type in an address, the game loads the photorealistic 3D tiles for that place, and enemies walk up the real roads towards your base.
The desktop app is the way to play: co-op lives there, everyone runs the same engine, and it keeps itself up to date. The browser version is for a quick look, solo.
Desktop onlyThis does not run on a phone. It streams photorealistic 3D tiles and puts thousands of enemies on screen, so it wants a fast CPU, a real GPU, a mouse and a keyboard. Open the page on a desktop and the downloads are there.
Before you can play you need your own Cesium ion token. It is free and takes two minutes, no card. How to get one. Made for desktop: it needs a fast CPU, a GPU and a mouse.
Work in progressUnfinished and unbalanced. Late waves get out of hand, some streets confuse the routing, and there are bugs I know about and more that I don't. It also wants a beefy machine: thousands of enemies on top of a live tile stream, and a slow CPU or a thin GPU turns the late waves into a slideshow. It's an evening project, not a release.
Towers, upgrades, research, a base to hold. Standard tower defense so far.
Nobody built the map. It is streamed from Google's Photorealistic 3D Tiles for whatever address you type in, and three things read that geometry straight off: where the enemies walk, what a tower can see, and where you are allowed to build.
The street graph comes from OpenStreetMap, the thin yellow lines in the picture. The cyan patches are building footprints from the same source. Ground enemies take the red route along those streets, flyers the magenta one straight across. Every waypoint of the ground route is raycast down onto the tile surface for its height, so it follows the actual terrain.
A tower only fires at what it can see. The surrounding tiles are rendered into a cubemap when the tower is placed, and again when its range grows; the depth is read back, and the result is kept as a visibility mask over the tower's range. Green cells are covered, red ones are blocked by a building.
Towers are set by raycasting against the tiles, not against a flat plane. Rooftops, embankments and bridges sit at their real height, which is why the same layout plays differently two streets over.
Forty seconds of unedited play in a residential street, debug windows open: the line of sight cubemap on the left, the frame budget beside it, the wave spawner below.
Two to four players defend one base in the same city. Each of you gets a road of your own: the enemies on your lane are yours to stop, you spend your own gold, and you may build anywhere, your partner's street included.
Co-op is in the desktop app, online through the public lobby or on your local network, where the host's app runs the relay itself. Every machine runs the whole game in lockstep; only the moves travel, plus the host's map and lines of sight.
Our first co-op match, Heilbronn, waves 1 to 38, narrated. Fifteen minutes on YouTube.
Anywhere Google has photorealistic 3D coverage works, most large cities and a good many smaller ones. How well it plays depends on where you point it. Some places load beautifully, others have tile geometry that makes the routing do slightly silly things.
Click any shot for the full frame.
The 3D tiles are billed per request, so there is no shared key. You play on your own Cesium ion token; the free tier is enough.
The token stays on your machine and is sent only to Cesium. It never reaches this site. A Google Maps API key works too.