Star Knightess Aura (henceforth SKA) is probably the best erotic game I've ever played. Its not for everyone, but for those its for, there is basically nothing else that scratches the itch.
SKA has two primary things as its draw
1) Slow-burn brainwashing where the protagonist goes from a frumpy nerdy heroic girl to a horny evil basic bitch.
2) A deep and difficult RPG where resources are limited and finite.
Virtually all of the negative reviews of this come from people who don't want 1 or 2. Which is fine, this game isn't for everyone, but if you aren't the target audience, you should give this game a pass, rather than think that the game is bad.
On the first front, the game is a real slow-burn. Not slow-burn in the kind of low-standards that people have of H-games, but in the sense of "it will likely be 10-20 hours of game time before you see a sex scene." There will be lewd scenes before that, but its meant to be slow brainwashing and that needs proper set up with smaller sexual actions first. So again, expect to wait quite a while on the protagonist to be doing more wild stuff.
Similarly, some people get upset because they feel bad making the protagonist evil. Its certainly fine if this isn't your thing, and it may be a reason to skip this game. But this doesn't reflect poorly on the game.
Mechanically, the game is very difficult, at least for a pure run (no corruption) on normal difficulty. If you want to play the game pure, you will need several runs where you learn and try out different builds and try to get things to work. This is a primary draw to the game. Of course, corruption allows you to bypass a lot of the difficulty. Story difficulty also trivializes things, if you personally don't want a challenge.
The game is, well, part of the game. I've seen other reviewers get annoyed by all of the "grinding" (which you literally can't do, resources are finite). I think what they are getting at is they don't like that they have to play the actual RPG. You are supposed to read the dialogue and see where to go next. Sometimes you will need to explore or use your mind to figure it out. You might need to try a different approach to a boss, maybe with a new skill. You can basically turn off the difficulty with story mode, but you are still expected to, well, play SKA. Again, this isn't a quick fap, and if that is what you are after, there are thousands of other games on this website for you.
But yeah, for anyone who finds either of my 1 or 2 to be up your alley, then I highly recommend trying the game out.