Before I get into the weeds, I should make it clear that I am not the target audience of SKA. I like wholesome and cuddly sex, antithetical to the corruption genre. So, I did not play this game for the lewd content. That said, I think SKA is among the best RPGM games ever created.
I'll call it a "strategic puzzle RPG", in that emphasis is on carefully managing your resources in order to overcome challenges as quickly as you can. Everything is a resource, and the most valuable of all is time. As days pass, the curse increases corruption and reduces willpower, and you will need to take actions that mitigate their effects. Furthermore, most actions that improve Aura's stats or learn new techniques end the current day, or take multiple days. Take to long to advance, and players will find themselves in a death spiral of low willpower - or lose outright from terminal corruption. If this happens, players can start a New Game Plus with boosted stats and/or carry over their skills, to help them get further next time. Lewd scenes can also help, as some of them provide powerful benefits - but can also incur hidden costs that weren't clear up front.
Combat is simple but challenging, and is based on targeting elemental weaknesses. Hitting an enemy with damage they are vulnerable to gives the attacker a Tactical Advantage, which both gives a significant evasion rate for one turn, and guarantees that a physical attack on that turn will critically hit. Vulnerabilities are mostly determined by species - for example, humans (including Aura) are resistant to light and weak to lightning, while plantoids are weak to fire. Furthermore, many enemies and bosses have some sort of gimmick that makes fighting them much easier once players figure it out. These can get esoteric, and it may not be clear if a given strategy is incorrect, if Aura isn't strong enough yet, or if RNG is being an asshole. If you're truly stuck, there's the option of tapping Aura's get-out-of-jail free card and activating Star Knightess... with a heavy cost in corruption.
While gameplay is SKA's strongest point, the writing isn't shabby either. Aura's personality is somewhat determined by player choice, but she's a solid protagonist who doesn't stop giving her all even in the face of constant setbacks and crushing odds. Alicia and demon king Richard foil her very well by being similar people - all three are arrogant, passionate, confident, and competitive, the difference being that Aura is selfless, and the other two are self centered. YMMV of course, sometimes Aura comes off as naive and overoptimistic, and she and Alicia get incredibly, ludicrously hammy when facing off. I can't really talk about the plot without spoiling the good stuff, but the connections between Earth and Roya go back much farther than they seem, and not all Royans are content to wait for the Hero to save them.
What really impresses me most about SKA is how the writing informs gameplay. If I haven't made it clear, the game is fucking hard, at least if you're gunning for the victory path. Leaning on Star Knightess for every major challenge will quickly swamp players with corruption. When the game says that the rules of the world itself stand against Aura, I believe it because the game is hostile to me as a player. When I see Aura struggling to succeed, I believe it because I have to struggle to succeed. When Aura is tempted to perform lewd actions she's not comfortable with for tangible gain, I understand her because I am tempted to have her do it too - and I really dislike the corruption theme!
I can't make any judgement on SKA's effectiveness as a lewd game, or a corruption game, but it is a phenomenal strategic RPG. Aura dev, you and your team have outdone yourselves.