Nice game! I played the web version as I'm on a mac without windows.
I like the music you added and the darker colour palette. The particle effects are also a nice touch.
Something that might be nice to add is a rewarding sound when you pick up power-ups that would make it more satisfying.
For the ground stomp and spike shield power-ups, I didn't understand how to use them.
I like how there's immediate feedback when an enemy has been hit by changing their colour from red to grey. However, I still struggled to tell how many hit points they have, and I think having a way to tell would be helpful. Such as a health bar or getting smaller after turning grey until they reach a specific size and break apart.
I'm under the impression the goal is to get a high score, and there is no end to the game - but I'm not 100% sure, so that's something you may want to consider making more clear in the game would be good.
Overall, I found it challenging and fun to see all the different power-ups and trying to get a higher score. I bet it would be fun to play co-op with friends and family as local multiplayer.