I defeated the big bug, grabbed the iron key and started my venture into the white void.
Had a lot of good fun with it, especially the fight with the final boss of the demo was very hype, keeping track of the environment while dodging it and swinging at it just. I was about to say the swinging animation could be faster, but I am not familiar with King's field, and judging from the other comments, that appears to be as intended. It does provide a nice contrast with faster slash and slash games, and I also think that gives it a nice strategic feel.
Also design-wise, I want to praise the funky slimes with their rainbow glitter going on, I liked the way they looked a lot. The overall "feel" of the world was perfect as well, with the fog, the dead trees and the fortress in the mountain.
All in all very promising prototype with a top atmosphere, hope you keep doing cool stuff with it!