None of this was exactly original: Honey Select models have been used a lot, a lot of games have a supernatural story built around an artifact or what-have-you, and even the mother-older sister-younger sister prevalent in all these games is only modified by the addition of a cousin, which isn't exactly novel.
But it's the QUALITY in which the game uses them that made me have to stop playing so I could leave a review.
--The Honey Select models are cute and sexy, and the sisters look like sisters without looking the same.
---Yes, the MC looks weird. But having played Honey Select, I know it's not Caribdis's fault. (SPOILER: Same reason I won't blame him if we don't get any visible pregnant content despite pregnancy being an optional part of the story. Honey Select has a mod where you can add a pregnant belly, but it acts as a shirt, limiting what you can do scene-wise.)
--More importantly, Caribdis seems to take absolutely full advantage of what HS can do in terms of posing, character expression, and storytelling. Every beat of a scene has an image, or just about.
--The storytelling is rather in depth, with so many little side stories (which make sense and add to the story, I thought).
--There are multiple paths, and the story ACTUALLY REFLECTS that. Choices matter. Which again shows the detail Caribdis put into this, making scenes for every path and combination of paths, in ways that don't make it feel like something huge is missing if you didn't take a path, and nothing feeling shoehorned in if you take every path.
---And another attention to detail that 99% of game makers probably wouldn't think about (in making a Renpy game, at least): there's at least one scene where the picture transitions are set to the music. It's hard to explain, but when you see it, you'll know what I mean. ...Maybe.
And the last thing, which for me is the greatest compliment I can give:
It's actually FUNNY. A lot of games try to be funny, but this is the first game where I actually LAUGHED. Caribdis seems to have a knack for comedic timing and balancing silliness with an otherwise dark and foreboding storyline. (I think he's English, though, so that might explain it.)
Maybe the best part, that's easy to miss: When that guy offers you a haircut, do NOT accept.