Yes, Musk reef would be a dungeon. I will probably put Aether as final boss, with the item that corrupts Lumine.
Aether in this game betrayed the will of abyss but many abyss mages still follow him. Then an altar (the will of the abyss) appeared on Dadaupa, trying to control the hilichurls to fight back. (I just made up this story)
battle UI: I am trying to rewrite that.
background and defensive building: In the future different places will have different terrain, and you can change them by construct defensive buildings
third katheryn to summon specific kinds of human troops:
Good idea,but I want one katheryn to unlock more detailed infomation, such as detailed buff value, skill info, catching rate, exact offspring percentage, etc, so maybe the fourth katheryn can do that.
get rid of hilichurl: Just sacrifice your girls using the alter.
special npcs CG: yes
About Rukkadehvatta:
Sure.