playkia I think I did misunderstand so just ignore, I thought you were talking about don't mention Unity for x reasons.
Can I ask something, have you even tried to make a simple game in Unity without any "extras"?
I have written a top down space shooter in 3D Unity that looks 2D in a couple days, but has all the benefits of 3D, audio, particles etc, what am I missing? I could even turn it into a 3D game down the road if it was "popular", not with 2D frameworks. (NOT USING MonoBehaviors)
My comment about runtime is just that, Unity at the core is just a renderer like all other game runtime/frameworks. If you take MonBehavior out of the equation and write your game like you would abstracted from the view, you get almost a Starling feeling in the code, at least that is my mileage.