By way of avva (Russian), I was pointed to this excellent analysis of Notch’s 4kb Javascript/Canvas demo of flying through a 3d labyrinth:
Per the Hacker News discussion, this is not necessarily the way you should be using canvas for 3d — that’s what WebGL is for — but seeing what’s possible with relatively simple code and the basic web technologies is inspiring.
(Notch is the creator of Minecraft.)