Epic Games has been wanting Unreal Engine in the web browser for quite some time now. Back in 2011, the company presented their Citadel demo running in Flash 11.2. A short while later, Mozilla and Epic ported it to raw JavaScript and WebGL. With the help of asm.js, which is a series of optimizations for JavaScript, Unreal Engine 3 was at home in the browser at near-native speed, with no plugins. Epic's Tim Sweeney and Mark Rein, in an interview with GamaSutra, said that Unreal Engine 4 will take it beyond a demo and target web browsers as a supported platform.

Today, Mozilla teases Unreal Engine 4 running in Firefox, ahead of GDC.

Speaking of speed, asm.js can now reach within 67% of native performance and Mozilla is still optimizing their compiler. While it is difficult to write asm.js-compliant code by hand, companies like Epic are simply compiling their existing C/C++ code through Emscripten into that optimized Javascript. If you have a bit of CPU overhead in your native application, it could little more than a compile away from running in the web browser, possibly any web browser on any platform, without plugins. This obviously has great implications for timeless classics that would otherwise outlive its host platform.

Both Mozilla and Epic will have demos in their booths on the conference floor.