Neat game, though i did find a gamebreaking bug. Heres some feedback
1)If you kill the big slime boss near the top of the screen, the smaller slimes it splits into will spawn outside of the level, so I couldnt kill them to progress
2) the ranged enemies that shoot at you will attack almost as soon as they spawn in which can be a bit unfair and frustrating. I recommend adding a timer so that the enemy cannot shoot at you for like at least half of a second after it respawns to give the player time to react
3) Getting duplicate weapons is a bit underwhelming. It would be nice if getting the same weapon twice would upgrade it, like giving it faster cooldowns on the main attack/ability, faster charge time, etc. Or add passive items that can spawn instead of weapons
Overall the combat is nice and you made great use of the art pack. Good job!