Parts of Engine

A Game engine is a bunch of code what works from behind the scene and responds to commands from the game code. For example game tells engine to create a game window, to draw an image on the screen, to play some sounds. The game engine is some kind of helper library for the game.

When creating such engine first problem is how to organize it's internals into logical subsystems. We need rendering subsystem, input subsystem, sound subsystem, sometimes physics subsystem and something responsible for the game loop. When I will create my engine I will probably start with subsystem responsible for creating game window and game loop, then I will concentrate on rendering and inputs. Last stage will be creating functionality to play sounds.