If you want to create your own game engine but aren't sure where to start I want to show you some practical concepts you can steal directly from the Doom engine source code and implement yourself. All of these will be language agnostic, so it doesn't matter if you're writing C or Python. And none of them have anything to do with 3D graphics, despite its status as one of the early 3D games I actually think Doom is the perfect case study for making your first 2D game engine.
