Dominic Szablewski released has posted a fun Typing of the Dead-style shoot'em up that you can play for free right now, so long as your browser supports HTML5. To play Z-Type, you simply need to type out the text attached to incoming ships/bullets. If you input the correct letters, you'll fire shots at enemies.

It's a simple vertical scrolling shmup with a single life and no bosses but a neat concept nonetheless. I only wish the difficulty ramped faster -- even at wave 40, it's way too easy to destroy all the enemies before they cross even a third of the screen. 

If you'd like to skip to the more challenging levels, this guy posted a Javascript snippet that you can put into your address bar once the game has loaded and skip to harder waves (change "10" to whatever wave you want to start at):

javascript:(function(){for(var i=0;i<10;i++){;}})()
Szablewski created Z-Type as part of the Mozilla Labs' "Game On" competition for creating "games built, delivered, and played on the open Web and the browser".

[Via @triptych]