Oof, this topic got hostile fast.
So right, it's kind of obvious that this game borrowed a lot of stuff heavily from Ultra Power. Granted, they added their own things that far expanded the game from it's original routes, but the core parts are still there from what I can tell. Normally I don't really care about people who use other assets to help build up a game (that's done a lot in visual games, especially on Steam), but in this case the source for the game was ordered not to be used by the original maker.
Honestly I'm not really that big on the sidescroller version of shooters (though thankfully this one lacks people getting ungodly defenses and hp). Considering the style you were shooting for, you really should change things up to be more top-down to encourage the exploration bit, with buildings and other structures to serve as cover/entry points into specialized areas. Would again fit the map style you are aiming for which just feels weird in 2d.