A common recommendation is not to write an engine, but to write a game instead. Create a Pong game. Create a 2D space shooter. Create a simple Mario-like 2D pla

A common recommendation is not to write an engine, but to write a game instead. Create a Pong game. Create a 2D space shooter. Create a simple Mario-like 2D platformer. Now take the code that is shared between all three projects - there's your game engine. Just extract that so that it's nicely separated and easily reusable in future projects.