HTML5 and the associated technologies are quite advanced at this point, but they're still not proven when it comes to games. Or rather, not yet proven, Atari's new games should make it clear that HTML5 gaming is not only possible, it's the way to go.
The games run great in IE10, Chrome and most other modern browsers, they make use of hardware acceleration and, the best part, they work with multi-touch input.
they developed for them. The video showcases the story behind the project.