Looks pretty nice so far! I really like the style of the placeholder art + music. Great atmosphere.
I think you have achieved your goal, it was simple but provided a challenge.
Perhaps you could recharge your energy over time instead of picking up magic pots (firing the staff is fun, but the mechanics make you not want to shoot unless you absolutely have to). It would also be nice with some gravity on the bullets, you could shoot up and over blocks (I can imagine it fitting in with the style of game your making).
Just some quick thoughts anyway, look forward to more!