WebGL relies on javascript to run. Looking at http://hellorun.helloenjoy.com/js/hellorun.min.js and searching for "png" you get images like http://hellorun.helloenjoy.com/assets/station/lightmap1024.j... which looks like a pre-lightning computed texture. Looking at the vertex data (in format x,y,z(,w)) there seem to be only 2048 defined vertices, which is a tiny amount for a 3d game.

Well, it was taking a long time to load for me so I looked at the network panel to see what was being loaded and I saw the lightmap. I have a little bit of a background in 3D graphics/game development so it instantly came to mind.