Nice game!
The theming may have been Castlevania with the subweapons but it felt like I was playing a Mario game (not a bad thing), with the coin rooms and bullets and such lol
* I liked the art on the enemies and character! Cute!
* The lack of music made me very sad. Maybe there is free chiptune music or something somewhere, this game deserved a banger song!
* The rotated pixels when you die are kind of impossible for the NES, tho it's a bit nitpicky. They break the pixel grid and the NES couldn't really rotate sprites so a more realistic approach would have been having it be limited to maybe 4-8 sprited frames. Other than that and the modern particles though I think the game felt very NES!
* I think the secrets were very well placed, discovering them felt pretty natural, I was surprised!
* I liked the patterns you came up with for the final boss, I wish he moved around a little more or had some sort of introduction, I was surprised when he was the end of the game.
Nice entry overall, good work!