Cool game! Managed to beat the boss on 2nd try.
First time on the boss battle I got it to about 30% health and then it disappeared for a bit and a dialogue showed up, but on my 2nd try this second phase did not happen and I was just a single fight from 100% to 0%. Not if that's how it's supposed to be or one of those was a bug :)
Also on the first enemy, the first time I played I was at 90% HP, I killed it, got the dialogue to continue but also somehow died at the same time - not sure how, because I killed the only enemy and I was almost at full health.
Music nicely puts you in a fighting mood :)
Controls feel a bit floaty, but I got used to it quite quickly.
At first I thought that the huge arrows are enemies and was shooting at them. Maybe making them a bit less threatening - not red and less saturated - would help.
Nice idea with adding fog to reduce visibility, but I think it could be toned down a bit. I mostly avoided fog completely, because I couldn't see anything in it and it didn't seem to affect the enemies.
Cheers!