This game was a lot of fun! Once you get a hang of the mechanics there's a lot of fun surprises to find in here!
If I had to make any suggestions, I'd say you should probably add some more interesting enemy variety. Maybe enemies that charge at you really quickly, or bullets that bounce off the wall. A lot of your enemy types just sort of strafe slowly and fire and that sort of repetitiveness doesn't bode well. You have a lot of variety in the environments and the type of weapons the player is using. but if the enemies don't really change much then a variety of weapons don't mean much. Maybe you get more of a variety if you play longer but I saw four or five areas and it felt like in every single one I was just seeing a lot of dudes strafing slowly and shooting a bullet or three. But your base here is really good. The weapons are fun and satisfying. One final recommendation would be to include something like a secondary spell, like a bomb of some type. That kind of variety makes the gameplay require that extra level of thought that will keep people engaged. Your art is lovely btw. Cheers!