Long story short: I'm giving it 1 star more than it deserves just because of art, and if you don't find this particular deviant-art/tumblr artsyle palatable you will just get shitty game.
You're getting into shoes of socially awkward virgin trying to bone his sister and being even more awkward towards other character(s). By awkward I mean: this is no anime-tier awkward, dumb or dense, this is straightforwardly on autism spectrum awkward. Sister is copy-paste tsundere archetype on side of tsun. You can excuse her shitty behaviour on account of autistic brother constantly trying to stick his dick wherever it doesn't belong. Take it or leave it, because you will click through dialogues and inner voices of MC for quite some time. It won't be quality.
Gameplay time, it's game after all. There is two parts to it: one is morning to evening routine, moving across rooms and doing stuff. Second one is sex game, and boy oh boy, what dissapointment it is.
Let's start with positive one, room traversal. It's all about random encounter, you might get to meet your sister in room or not, all depends of her fixed routine and dice roll, whatever she's doing is also random so it might time to get scenes you want. Each room has activity that will boost your relationship status with sister or increase some stat gain (for one day). Also you can search for items - but don't bother, I got one playthrough this way and it doesn't change much, basically it's yet another layer of unnecessary randomness that doesn't add to the game. Chances are low (for quality items there basically gatcha-tier chance) and sister can always appear and steal shit from you. Bother not.
You will use sex "game" only for increasing some semi-explained statuses. Most of them is useless. You want to unlock one of them to see her awake metter, then you see how often you can click.
It's not a game. It's annoyance. You don't get rewarded. You just wait till meter decreases so you can safely click body part and get away with it - and then you run out of action points. Everything is then converted to points you can distribute among your stats. Rinse and repeat. You might see guide on this one because it's such a chore and, unfortunatelly, story is locked behind some stats so I wish you happy grinding.
And don't expect much of sexual content, it's lower quality than most oldchool flash games.
Speaking of gaming, do you own powerful rig? It doesn't matter, really. You will get loading times of AAA games EVERY time you change room. Or day. I hope you enjoy waiting.
Last one thing is developement process, and sweet Lord, this is something else. At least 50 pages of comments is dedicated to waiting and moaning "where is dev", "where is update", "am I wasting my money on patreon" and when update finally drops after 6 months or so it's underwhelming, "wow it's fucking nothing" kind of update. It also broke gallery so... you get an idea. You will probably never get finished product out of it. Every update might be last one, by looks of things.
Overall: Don't bother. Most importantly don't ever pay for it, EVER. If you want to play it you will pay with your precious time anyway but I don't think you can sue developer to give it back. The only thing this game is doing the best is cock blocking you - on many, many levels - and if you're into this kind of stuff you've just found your favourite game. Enjoy.