Yeah Mothic is my first attempt at an engine. It's moreso just a framework right now as I've only been working on it for 2-3 months. And doing this game jam in Mothic has shown me how inadequate and terrible it is right now haha. Many things to improve before it becomes public (even though this stripped down version is sorta public now lol).
Thanks for your compliments! Gradius is indeed a bit of an old game to play these days, but I enjoy some good retro games.