Here I was getting ready to crack a joke about the CGs in the preview pics looking like they were drawn in MS Paint, only to scroll down and see everybody praising this game as a classic. Okay, you've piqued my curiosity, guess I'll download it.
Yeah, scenes are mainly static "retro" CGs (with some pan/scan/zoom effects) and text. However, the bulk of the game's H are very well done dot-ero animations that happen during normal gameplay. This game can be considered one of the inspirations for games like Zell23's (Forest of Blue Skin, Succubus Affection, etc).
Without giving too much of the plot away, its a metroidvania. A boy finds himself in a castle full of lusty monstergirls. However, he's pretty powerless and can't do much other than run around and try to cover his boybits. Over the course of the game, however, he can transform into girls with different powers that aid in exploration and can attack and whatnot.
You have four attributes: health (red bar), magic (blue bar), lust (pink heart) and energy (white bar). While transformed, any damage taken decreases your blue bar. If this gets depleted, the transformation ends and you're a helpless boy again. In THIS state, any damage decreases health instead, and when that depletes, its game over, HOWEVER, while most enemies are violent while you're in girl form, many instead become.. amorous while you're in boy form and.. well, you can figure out the rest.