Just got around to checking this out, having played Castle of Temptation in the past. Great sprite work and general production quality but unfortunately, as others have said, the gameplay is very poor for how much breadth there is to the mechanics of it.
There are some very specific co-op animations in the gallery viewer you'll probably never see in-game without deliberately setting up to see them, since one or both of the attackers are ranged spellcasters that support but rarely grapple. In particular a couple of milking ones involving the sorcerer apprentices + harpy. Of course, actually viewing animations within a level during gameplay is a pain in the ass regardless. One of very few games where I'd suggest just downloading a full save and using it as a gallery viewer which is a real shame. The plot and writing are kind of cute.
Edit: also, having a femdom game where the protagonist is a devil guy who never appears outside of cutscenes, the controlled character is a tiny cartoon bat that acts as a mouse cursor and strategist, the allies automatically attacking on your team are the girls, and the enemy are cannon fodder generic warrior/archer guys... What a strange choice. While it's not my preferred setup, it does work ok, it's just a really bizarre choice.