So many techniques that made web games good, in terms of smart loading, have been lost or abandoned since the mid-2000s when bandwidth limitations were common, and at the same time "engines" like Away3D and Starling were starting to leverage AS3's ability to handle async calls and async uploads to the GPU. JS engines now try to bundle that behavior into asynchronous asset loading calls, but it's not ever really dialed in to make sure you don't experience freezes or hiccups in gameplay, so usually it's loaded by game level and not fluidly as you move around a world. It's not as if the authors of this game couldn't have put it all in a 17.5 MB package, and most people wouldn't have noticed anymore because the world has gotten used to long initialization screens. What's awesome is to see someone do the art of lazy loading so elegantly.