Doom on the Web

Doom on the Web was a demo created by Firefox Mobile programmer Alon Zakai to help demonstrate then-emergent new in-browser and cross-language compiler technologies relating to the  language. It was uploaded to the Mozilla Hacks website on June 2, 2011, and was taken down within 24 hours after receipt of a notice by Mozilla from ZeniMax Media.

Technology
The Linux Doom source code, with minimal modifications and the addition of supporting HTML architecture for website hosting, was compiled and translated from C into JavaScript using the Emscripten cross-compiler together with Clang, and then subsequently optimized using the Google Closure Compiler. It was primarily designed as a demonstration of the speed and versatility of a combination of the HTML canvas element with the then-new typed array feature in JavaScript, enabling an efficient frame buffer representation.

Takedown
ZeniMax Media alleged that distribution of the otherwise free-of-charge and widely available nine-level shareware IWAD over the web in an automated fashion was a copyright violation, and additionally contested the name of the port, claiming that it constituted trademark violation. Mozilla was forced to take the demo down from their web page, though its source code remained available for a long period of time as it was not part of the allegedly illegal content.