A new version of the game SimCity was recently released. Its UI was done entirely in JS, running on Webkit.
Steven Wittens explains the draw of using HTML in native games:
I wonder for example how many hours of dev time the game industry has spent reinventing the wheel for fonts, menus, option screens, etc. To be fair, they often do so with amazing production value. But guess what: you now have CSS 3D, and soon you’ll have CSS shaders. You don’t need custom in-house tools when your designers can just use Chrome’s Inspector and get the exact same result.