So, I am one of those people that wrote a game engine from scratch, in Java. While I'm glad I got it as far as I did, with the advent of Java 9 modularity and lacking Windows hardware... that path was quickly becoming a dead-end. Making matters worse: Huge inertia for Swing GUIs hindering my ability to think in terms of traditional game engines.

Switched to a traditional one despite this (Love2D)... and once I overcame the initial learning curve, I realized what I'd been missing: joypad support, easily going full screen, and the ability to release for mobile devices. Wow! I should have taken that risk sooner, but my brain was stuck inside a box and couldn't see the exit though it was right in front of me the whole time...

Now I'm working on 2 games in this new engine, and the nice thing about doing that is learning something for one game often helps the other one, too - meaning faster progress for the pair together than separately.