To me, the biggest appeal of this game is how satisfying it feels to corrupt the heroines. There are 6 of them and hey all have distinct, strong personalities that made me look forward to seeing each of them get degraded into lowly slaves. They're capable, fierce, and in the main route they're written in a way that they represent a credible threat and challenge for the protagonist to overcome, especially in the original route where the protagonist has less resources and has to rely on his wits and cunning.
The women are brainwashed one by one and used as agents against their former allies, with changes in their appearance to reflect their changed allegiance. I live for this kind of thing.
Another thing I really like about this game is that it has a setting that feels lived-in. It's not original, by any means - in fact, it wears its references on its sleeve -, but besides the world's background being well explored, character motivations, backstories and interactions all feel real and like these characters do have shared histories and relationships. Moreover, not everything revolves around sex. It might sound weird to praise this in an erotic game, but what I mean is that it feels like the sexual and non-sexual elements of the story feel symbiotic, one builds off the other, instead of the plot feeling like an excuse or something that is tacked on for the sake of sex. Feels like a political power struggle that would happen regardless of the whole sex slave angle. Conversely, things go in the direction they go because a slaver ring is involved and because the protagonist has the interests and proclivities he has. One side props up the other which is something you rarely see in other games.
If you want a game that dives straight into the sexy times, this might not be for you, but if you're into your mind control/corruption stories being built on a sturdy and reasonably interesting foundation, it's one of the best available here in my opinion.
There are two distinct routes, one where you play as a corrupt Archbishop scheming to turn the queen and her inner circle into sex slaves, and other where you play as a cyborg part of an invasion force who wants to capture and convert these same women for his organization. Pretty different vibes, I prefer the archbishop's route, which is the original and the longer of the two - the Inquisitor/Cyborg route is basically a DLC/expansion.
I do have to bring up a negative though: there are grammar and spelling mistakes aplenty. They're minor errors, nothing that gets in the way of reading comprehension, but they happen often. And that's bound to bother people. English is a second language to me so I'm not really upset by these mistakes, but the fact I caught them as often as I did speaks to their frequency. It's a sad blemish on a game that still, despite that, has the writing as its strongest suit.
The visuals use Honey Select 2 and it looks pretty damn good - there are some issues with hair textures here and there and some minor clipping (especially with capes), but nothing that presents a real issue or takes away from it unless these things really bother you. And for the textures, there are the upscale mods.
This is one of my favorite games here on F95 and I strongly recommend it to anyone into mind control, and especially to anyone who liked the Kangoku Senkan/Prison Battleship series, as it seems to be a major influence on both this game and its predecessor, Isis - The Fall (which I also recommend, by the way).