Mozilla announced today that it has been working in collaboration with high-end video game engine developers like Unity Technologies and Epic Games to bring high-end games to the Firefox browser without having to install plugins. Available today, the Unity 5 engine has a WebGL export preview function, while Epic Games has added a beta HTML5 exporter to Unreal Engine 4.7, which is especially interesting since the engine has become free to use.
Judging from the demonstration videos, the future of web-based games could become very impressive, and hassle-free for both gamers and developers. But you don't have to trust the videos. A few Unity game examples have been exported to WebGL, and they're ready to try out.
Source: Mozilla Blog