Hadn't heard of this one before I saw it in some news.yc comments:
Our mission is to create one of the most powerful, beautiful, and simple Web rendering engines in the world. Our passion is to make it completely open and free for everyone. We are artists, developers, creators, and dreamers and we want to make it as simple as possible to enable everyone to bring their ideas to life. With this new version of Babylon.js, we set out to make it even easier to develop with. From a ton of new tools, to improved workflows and features, new documentation and more, it is our sincere hope that Babylon.js 4.2 will make your development process faster and easier while unlocking new simple ways to work.