Decent game idea! Enemy variation is something good in this; plus a boss fight is always nice. That and the audio was quite enjoyable! I noticed how the music picked up as I went on, adaptive music is always a treat. My main complaint though is that I never really felt the need to do much other than hold the attack button; by doing so I felt like most of the game and its level design became very trivialized. I would maybe have an attack cooldown to avoid this! That would allow the enemies to approach you more, and thus give the shield more use cases.