Cory Doctorow at boingboing points to this amazing little game:
URL Hunter: http://probablyinteractive.com/url-hunter
Video game in your browser's location bar:
Probably Corey's (sic. Should read Probably Interactive's) HTML 5 video-game 'URL Hunter' takes place entirely in the URL bar of your browser, in which you must chase down rogue 'a's with your mighty 'O' and clobber them with the spacebar. I keep running into croggling demos of HTML5's capabilities -- last week in Toronto, Mozilla.org's Brett Gaylor showed me a WebGL demo that left me with my jaw on the floor. It's going to be a cool couple of Web-years, most surely.