Have you tried Phaser2D? I use it sometimes since you can build super fast web games with it^^ I have never heard of Blitz3D but it looks interesting. Luckily, different types of engines and frameworks are abundant these days ;)
I think I once tried it few years ago. Recently I really enjoyed to write my own engine, as HTML5 makes it so easy - except for CORS and no-user-interaction restrictions. You can't just play a sound these days, or lock the mouse. The user must click something before, otherwise it's blocked.
