Ejecta is actually pretty cool. It maps all the ImpactJS render calls to native OpenGL draws plus other stuff like that.
> JavaScript code is executed directly by a JavaScript VM (JavaScriptCore), the HTML5 Canvas 2D and WebGL API is implemented in native code with OpenGL, Audio is implemented with OpenAL. Several other APIs (touch, accelerometer, localStorage, gamepad) behave like those in a real browser.
So I solves a lot of pain points and the only problem you are left with is dealing with JavaScript? It's quite neat, but why not simply use a better language and an engine? E.g. Unity3d, MonoGame, Godot?
If you're targeting the web, then you're compiling to Javascript anyways, so the indirection + engine complexity isn't always worth it. Unity tends to pay off as you take on more platform targets and/or implementation complexity (like graphics), for example.
It's kinda like using https://github.com/schteppe/p2.js for physics instead of Box2D: if p2 gets the job done, then you get the advantage of working with a much simpler code base than Box2D which is just about impenetrable as an emscripten port.
> JavaScript code is executed directly by a JavaScript VM (JavaScriptCore), the HTML5 Canvas 2D and WebGL API is implemented in native code with OpenGL, Audio is implemented with OpenAL. Several other APIs (touch, accelerometer, localStorage, gamepad) behave like those in a real browser.
http://impactjs.com/ejecta