Sprite work, music and sound effects are all top notch
However, the actual gameplay seems to have taken a hit in exchange. While movement is fine, the combat suffers in multiple aspects. To begin with, the only way to engage enemies is to also move into their attacking range, which often leads to trading damage with an enemy. With the amount of enemies in each stage, trying to engage every one of them leads to inconsistent damage trading and in the multiple attempts to run through your game that I did, it often didn't allow me to progress past the first stage.
On top of this, the lack of any damage indicator makes it hard to know when I've actually hit an enemy, or how much health they have remaining. This would lead to me trying to edge up to an approaching enemy and mindlessly mashing the spacebar, hoping that I might be able to scrape past before the enemy attacks me back. I should also add that backing off after an attack to make the engagement "safe" on the player's end becomes difficult, as enemies spawn in behind you. This can quickly lead to either being backed into a corner or completely surrounded, however I did notice that turning away to look at enemies behind you would prevent any enemies from the front from moving closer to you, which at least prevented the issue from becoming worse.
Another thing to mention is the lack of any "Controls" display from what I could see (please tell me if I missed it somehow, I will go back and replay the game). While I was able to figure out movement and attacking with the spacebar, I was unable to know if their were any other player actions.
Assuming that this doesn't already exist, I believe a few of the gameplay problems focusing around actual "safe" engagements could be solved by adding a ranged attack to the player of some description, perhaps with a cooldown to prevent it from being spammed to much and making enemy approaches too "safe".
Aside from the aforementioned issues I see with the gameplay, I should really stress that I loved the spritework and general aesthetic of your game. If I have missed anything that you believe would have made my experience better, please let me know and I'll replay your game right away.