Have you had the idea of maybe creating your own engine? Or is that something that is implausible?
Possibility Of Engine
I don’t quite understand the question. We did create our own engine 
If you’re referring to the “flixel engine” that we used (and which I sometimes call it), then it might just be splitting hairs on terminology. Most correctly, flixel is more of a “framework” rather than an “engine.” So, if you mean engine like, “the source engine” or “the doom 3 engine” then the defender’s quest codebase is an “engine” and flixel is just a framework like openGL.
If by “engine” you mean any middleware or code library that handles graphics/blitting, then yeah that refers to what flixel is, and we’d much rather use existing blitting “engines” than write our own, if that answers the question