How to Make a basic web game with no plugins using only HTML5 and Javascript

Making web games using Flash and all the other plugins out there is fine, but compatibility and resource use are always going to be issues for them. Amazingly enough though, HTML5 is far enough along now that someone has made BioLab Disaster, one of the first if not the first web game to be made entirely with HTML5 and Javascript with zero plugins. The game's maker, Dominic Szablewski, was nice enough to make this video describing what he did to program this landmark game. It even describes why this game is like Super Mario World, with examples.