Your browser won't switch on 3D graphics (WebGL 2), and the game can't run without them. One of these usually fixes it:

1. Turn on hardware acceleration. Chrome, Edge, Brave, Opera: Settings → System → “Use graphics acceleration when available”, then Relaunch.
2. Quit the browser completely and open it again. After a graphics crash, browsers block 3D until they restart.
3. Update your graphics driver and browser, or try another browser (Firefox if Chrome won't, or the other way round).

To check, open get.webgl.org/webgl2: it shows a spinning cube when 3D works.