Great game.
Lots of moving parts, dynamic features, interesting gimmicks for your character (by which I mean reload) and the enemies. I actually don't think you should do away with any of them, this large repertoire is your charm. What is actually hindering the game is the HP. You're putting on a great show, but sending the player back to the start after one of the many fun moving parts you created takes them by surprise turns it into grand guignol. The invincibility command showed me how that's what actually should be done with.
Make it a point system and let people die freely and just respawn (you know how it is with those good cowboys they never die for real) and see your show to the end, and just get a bad score for it (See: Metal Slug). If you want people to engage seriously with the game, lock a cutscene or image behind a good rank to motivate them to try harder. Anything but a game over that keeps us from playing with all the great toys you've made, and can still make. I'm sure that removing the game over will conversely let your imagination run even more freely and let you develop even more creative, interactive fun stages and set pieces.
Break the mold of your standard game and it'll really elevate your art, trust me, you're already doing a fantastic job, what's hindering you is common sense of the industry.