Game Engine

the core part of a game engine is a renderer, a physics system, and other more complicated things like AI. Games that run on the same engine will have similar physics and Artificial intelligence, though those values can still be tweaked by developers

if a development team desires to make a game using two different engines, but using the same assets and textures, the game will look exactly the same. The engine's job is to load the images created by the artists.

  • consider that Gimp, windows media player, photoshop all load an image and look exactly the same, even though they're not the same program.

Making your own?

a game engine is just a bunch of convenience classes and structural decisions for common tasks in games. If you want to do it without an engine, you have to write all those classes and make those decisions yourself.