I noticed that your textures are not sharp. You can change that if you select the sprite asset and change the filter mode from "Bilinear" to "Point (no filter)".
Projectiles at the beginning were very slow. I could easily outrun my own arrow. Then the lasers caught me by surprise when they fired at actual projectile speed.
The view felt a little to narrow. I didn't want to come closer to the "boss", because that would leave me with no time to react. So I ended up shooting in their general direction without seeing them.
The character sprites could use some outlines this should be an easy shader to make.
Usually walking back in games is considered boring and that's why all dungeons have a portal at the end that takes you back. If you insist on walking back you need to make it engaging as well.