This isn't gonna be the most coherent review, but after spending several hours doing many dozen runs and discovering the ins and outs of this demo, I have some input.
To start off with some good; the concept and the art is great. The animations are nice, though I sincerely hope that grabs get animated in the future (the idle being an animation, restrained by tentacles (the stun) is animated, but actual penetrative grabs are not) as that would drastically improve the adult aspects of the game. Also, it's hard to tell what's happening with attacks as things like the harassment sprite only flashes for a fraction of a second whenever a girl gets hit.
The game overall is fun, though the learning curve is steep and it feels like there's a lot of discrepancy in build viability - sometimes you get get a good skill, like multishot, at the start of the run and you just breeze through the whole thing, sometimes you don't get any AoE skills at all and you get hopelessly overwhelmed immediately with no counterplay. Something to smooth out those power levels could go a long way. Or you could slow down the enemy spawns, they get to be too much extremely fast.
The capture mechanic is a great idea, though I'm not 100% on the current implementation. If a girl's "health" runs out a single time, they're completely gone, out of the fight permanently, and without their additional dps you simply cannot keep up with the endlessly spawning mobs. Yeah, you can rescue the girls at the slaver later, but that means actually surviving long enough to get there... and with the spawnrate of enemies? That's not going to happen unless you're impossibly lucky, or cheating.
The bosses were interesting and there was some nice variety, though it hurt me physically to see they didn't have any unique grabs or animations - the closest to this was the slaver who summons a unique minion - the imps - with a unique grab (that said, the imps have my favourite of the grabs, especially the gangbang on the archer.)
I should also mention a number of recurring bugs - softlocks, specifically. They're easily replicatable, at least in my experience, so I'll lay out the ones I kept running into.
First is that any sort of multi-hit move, like the knights "hit 4 enemies in the red zone" or the ninja's "attack 5 random targets in the blue zone" will guaranteed softlock if it runs out of targets when it isn't expecting to - this kept happening to me against the bomb thrower boss, as the skill killed a bomb that destroyed the other, adjacent bombs, thereby instantly clearing the entire zone - except the skill is still trying to attack a target that isn't there, softlocking the game. This can be avoided by just not using these abilities, but if you ever forget and it happens, your only solution is to X out of the game and try again on a new run.
The other softlock I kept running into is if your last "active" girl is stunning, disabled or otherwise unable to act (but not out of health or resist) then the game softlocks on your turn - the game is waiting for the player to take their turn, only they can't select any characters, so nothing can happen and your only choice to to close the game. This one's particularly frustrating beccause unlike the other softlock, this one just kind of happens on it's own sometimes - you can't just decide not get stunned, it's the enemy's turn.
It would also be nice if there was some discernable sense of progress, as it is right now there's no way to know how close you are to actually hitting your next interactible location at any given wave. You really just just keep kiling things and praying you get your payout soon(tm.)
Again though, the art is great, I'm not a particular fan of the permanent helmet on the knight, but the ninja and archer are perfectly within my strikezone, and that ninja's idle animation is downright hypnotic... the version in her slave gear is also a treat. It took a long time, but I eventually ran into a situation where I saw two of the girls getting raped in slave gear and was pleasantly surprised to see different grabs, which I hope is a trend continued in the future.
Overall it's a promising start, and I do like it a lot, though there's a lot of stuff to improve. More than anything, I'm just hoping it gets more content - more grabs, some actual game-over cgs (despite all my runs, all my efforts, I could only find the one generic "chained up and surrounded by sillhouettes" game over - I was at least hoping the bosses would have something unique).
Side note but the item shop actually got a chuckle out of me - basically a giant neon sign that says "META PROGRESSION HERE" hanging over a bunch of empty shelves.
tl;dr: The ideas are great, the art's good, it needs polish, bugfixing and a lot more content.