Cool little game. I completed all 3 levels.
Three points of feedback I would give are that it doesn't have the traditional power increase that roguelites are known for, it would be nice to have a dodge or block or something, and reloading feels like it serves no purpose.
First, it kind of misses one of the biggest parts of both of the games that it was inspired by. Powering up through artifacts and levels. When the crowds started to pile up all around the boss I wasn't sure if it was going to be possible. It ends up devolving into just running in circles hoping some of your bullets make it to the boss before they kill you. It really felt like I needed something to cut through the crowds, but with enough time eventually enough bullets hit the bosses to kill them. I think if enemies were dropping something to pick up to allow you to power up, be it different weapons, weapon upgrades, damage boosts, anything to spice it up a little bit that would be cool. As of now it feels like enemies get more powerful and numerous based on time like RoR, but without you also getting more powerful by defeating them and collecting artifacts.
Second adding in a dodge or block or some other mechanic besides movement would improve the game feel a lot. Sometimes the enemy bullets are coming in too fast to change course to avoid them but a dodge would alleviate that a little bit.
Finally reloading feels bad. It takes so long and doesn't really serve any purpose other than slowing down the gameplay. I think if you wanted to keep reloading you should make it take less time or add in a little QTE for reloading that can make you reload faster and deal more damage or if it is failed reload normal speed with no damage boost. Anything to make it feel a little nicer. I think the game might feel a little better without reloading but if the reloading served to make you stronger somehow that would be cool, some upgrades (like artifacts or level bonuses) around reloading might be nice, like a damage pulse when you reload or something.
Also the tilting the enemies get when they target you is because you are taking into account the y position of the player when pointing them at the player. You could fix that by just removing the y component of the look direction check, but I'm guessing you saw it and kind of thought it was neat feature so kept it in.
I'm sure it was on your list but different weapons would be cool too.