I think it's a testament to this community's kindness and love of free porn games that the rating for this game is as high as it has been so far. Unfortunately, I'm neither kind nor desperate enough for this game in its current form to not be brutally honest. And I have a LOT of honesty to share.
This is not a four star game; It's a learner's project, currently worth two stars at best, and the three reviewers before me should be ashamed for their lack of standards. It serves no one if the developer doesn't learn what's good or bad.
So let's talk about it. A lot. Probably more than it deserves.
WRITING:
There's nothing wrong with the general premise. Demons, magical marks of ownership, succumbing to lustful desire -- these are all tried and true tropes of the porn game genre, and they all happen to work pretty well. No need to adjust the basic premise except to perhaps spice it all up with a bit more detail. For instance, what is our character's name? Why did the high-demon let her go or lose her in the first place? What makes the merchant so shady? Is it that he spits wicked lyrical bars, or does he have a quest for us that ends with a little Sunday morning BDSM? A little more context could serve in making the rape itself more impactful or interesting. Context is hot.
That having been said, the real problem with the writing in this game is the grammar, or rather, the lack of it. It's deeply distracting to have constant, basic grammatical mistakes in the text. I can't take anything even semi-seriously with every single character's text blurb reading like a six year old's "What I Did Over Summer Vacation" assignment. An apostrophe or two, proper sentence structure, and some post-comma spacing would go a long way to improving the writing. Grammar is hot.
It doesn't need a lot. It's a porn game. There's more important things than the writing.
GAMEPLAY:
It's almost okay. I've played a few sidescrolling sorta-fighters before, and this checks a couple of the boxes. I do think there's a couple fundamental issues, though.
The movement feels perfectly responsive, as in "the character responds more or less how I want when I press a button", but the basic walking speed feels a little slow. I'd chalk this up to the character scale/camera zoom and background scrolling speed giving just the impression of slowness. It could help a lot to pan the camera back a bit and make the background to scroll a little faster to change the impression of slowness.
Also, consider lowering the stamina and magic available to the player. It's very easy to spam the slide or thrust attacks currently, and those are also the only techniques necessary for fighting anything. A little tweaking can go a long way.
INTERMISSION/CONJECTURE:
Actual porn games are rather rare on this site, since the majority of projects coming along are either Renpy VNs with posable 3D assets or RPGMaker projects with artwork only marginally better than this. Of course actual gameplay would be a breath of fresh air in the stale miasma that is the porn game market. Most people will express genuine relief that someone wants to make an actual game rather than another digital picture book.
No, the real problem with this game is so stupidly obvious that I feel tacky just saying it, but let's get it over with so I don't give anyone the false impression that I'm delusional; the artwork in this game sucks more dick than its characters.
ART/ANIMATIONS:
I mean, this is jaw-droppingly bad. It might actually be the worst game art I've ever seen. Even some of the worst NES games ever made are better looking than this. I'd rather play and wank it to a text game than this game -- actually, have you ever heard of Corrupted Saviors? No art in that game whatsoever, but it's far more erotic to me than this. Go play that game if you get the chance. It won't help you with this, but it's a banger.
Anyways, back to bitching. I've done doodles in Microsoft Paint that were better than this, and I strongly suspect that's what the developer used. The characters look, generously, like Adult Swim cartoons at best. Think Dr. Katz or Home Movies. Those cartoons were intentionally drawn badly because it's a stylistic choice to indicate that they weren't meant to be taken seriously. This is even worse than that.
Let's look at the protagonist. Those boobs look like whoopee cushions, the shoulders are ill-defined if they even choose to exist, the arms are super thin, the abdomen stretches like play-doh... there's just so many problems in your proportions that I'm flabbergasted. Have you looked at a human body? Hell, have you even watched a cartoon before? There's a minimum threshold for masturbatable content, and it's surprisingly low, but not even close to this low.
The animations don't help. Everything is stilted, it all moves and deforms too little, only vaguely implies what we're supposed to be seeing, and the sexual animations are over within 5-10 frames rather than repeating long enough or remaining still enough for one to mentally register whatever had even just occurred. It's nice that some consideration was given in animating each scene seperately, but it was not worth the effort as the game currently looks. Sorry.
CONCLUSION:
Look, the extra costs in time and effort to complete good artwork and animations are big. It's the reason why most porn games default to VNs and RPGMaker. Stills are easier to make than proper animations.
This project is perfectly fine as a proof of concept, but it completely sucks as a porn game. It NEEDS better art. Everything else I've mentioned can go to the wayside as long as you're willing to either completely re-draw and re-animate this yourself, or willing to commission someone to take your animation frames and completely re-finish them, but it needs a far more professional touch. As it exists right now, this is unfappable, and barely playable.