There's been a recent surge in HTML5 development thanks in large part to Apple not supporting Flash for its iPad.
A group working at Google decided to devote their 20 percent time to making a version of Quake II that's playable through an HTML5-compatible browser without the need for a plugin.
Google's Chris Ramsdale wrote in a blog post:
We started with the existing Jake2 Java port of the Quake II engine, then used the Google Web Toolkit (along with WebGL, WebSockets, and a lot of refactoring) to cross-compile it into Javascript. You can see the results in the video above -- we were honestly a bit surprised when we saw it pushing over 30 frames per second on our laptops (your mileage may vary)!It's still early days for WebGL, so you won't be able to run it without a bleeding edge browser, but if you'd like to check out the code and give it a whirl yourself, you can find it here. Enjoy!
While we've seen more impressive efforts from a browser through id Software's Quake Live, it requires a special custom plugin. This work from Google showing off HTML5 bypasses the need for custom software and plays it through right into Safari or Chrome. Sadly, Firefox doesn't support the necessary HTML5 required for this tech demo.