Am I going crazy or haven't I used websites that update the favicon to indicate things like new notifications?
Here's a 16x16 pixel game of Defender implemented by animating the favicon: http://www.p01.org/defender_of_the_favicon/
Here's a 16x16 pixel game of Defender implemented by animating the favicon: http://www.p01.org/defender_of_the_favicon/
The few websites I first checked, like Facebook, I must've misremembered. But it's definitely still out there in the wild.