While the idea of using private info for manipulative conversation in the hand of a MC who's actually socially aware is far more entertaining than a creep who blackmails the girls immediately as he got them like your typical NTR doujin protagonist... this game leaves much to be desired that I'd rather it consist of you raping the girls with said blackmail material instead.
The game has two route, one is "blackmail" which should be self-explanatory, while the other is "confession" where you rizz up the girls you're stalking on with the topics you've gathered that differentiate it from most other voyeur games. But the thing is, the game raises your affection with the sister regardless what topic you brought up. They don't seem to ever react negatively, even when they made a fool of themselves by bringing up their panties or boobies despite the large amount of topics, while I get it would be frustrating if one has to reload and select a different option to keep their affection up... it's the essence of dating sim, by not punishing the player, you're taken the most minuscule amount of gameplay into something more like a routineus labor to see more dialogue as if it's a gacha game.
Even the blackmail route isn't much better as it's also just grinding for points, you set up only 1 camera per day unlike other voyeur games with them spy cams, which just makes things dull and boring than feeling as if it's rewarding to see another scene. Especially when it comes to shared rooms like the shower where you have no control over which sister you're going to see washing herself, which I find incredibly stupid.
Despite the daring premise, it's basically "grind points for a single scene" the game. If the story and writing of the dialogue were better, I may find it more worth the trouble. But no, it's extremely generic and mid to the extreme. The two sisters have generic traits such as "likes to eat", "extroverted", "doesn't like pepper" that's all very separated from scene to scene and dialogue to dialogue that doesn't make them feel like characters. Like I aforementioned, the sister sometimes blur out their own secrets themselves without much of a filter, which I do get sometimes... but it really takes the fun out of knowing these "private info" if they'll just say it to their next door neighbor whom they barely know, and treat them as if they're already a good friend that's "fine" to know about this thing.
Besides, if the dev really wanted the game's script to be the primary focus, then maybe don't have a 1 minute time limit where I'm at no risk of getting caught? I had to mash through all the details of their daily life that they must have taken a lot of effort for like a speedrunner, because otherwise I'd just collect one or two topic at most. Like, this isn't a gameplay focused game, why have such a strict time limit?
Even the endings suck, on lover route they just become MC's sluts for talking to them for ten times as if he's a Persona/Danganronpa protagonist, the "blackmail" route also has them becoming his bimbo whores... after he knocked them out and raped them? What? The route says it's blackmail, yet the blackmail comes after you raped and broke them? It just doesn't make much sense whatsoever.
The only saving grace is that the art is neat, but I'd rather the artist used their talent for better projects for this otherwise low effort game. If you like voyeur, maybe this is for you, but I advise that you go out and find better voyeur games.