Cool little entry. Despite how corny they sound, I like that you've made most of your SFX yourselves. The visuals are also extremely charming.
I've managed to get all 4 endings and hoped that I could find a secret one. I've tried killing every characters with only the fireball and fighting the skeleton in the shack, but nope. I'm not sure the second one is even possible.
I love games where the player can fight bosses in any order so I'm partial to this, but I really liked your take on the theme. Every character was challenging in its own right. I feel like the cat's heal spell is by far the most useful one apart from the fireball however. I rarely, if ever, used the poison cloud and the lighting strike.
My biggest gripe with the game is the size of your map and how empty it is. I kept getting lost even after four playthrough and it became tedious pretty quickly. I feel like a smaller, more condensed map (or 4 tiny rooms) would be a better fit for what you're going for.
Still, really nice job.