This game is a tragic combination of fantastic assets coupled with completely nails-on-chalkboard gameplay. To save yourselves some pain, do this: after starting the game, walk onto the magic circle near the Lustkeeper (after tutorial) and go to the top-left corner in the weird mansion place. You'll be able to access (most?) of the sex scenes there and skip the gameplay, though you probably miss out on some other stuff doing it like this. I don't advise actually trying to progress through the game naturally. Keep reading for a more detailed review...
The game is heavily Dark Souls 2 inspired, even containing a Majula-like hub area and Dark Souls easter-eggs like the pig(s) that can kick your ass. It tries to emulate a lot of what Dark Souls does; unforgiving gameplay, enemies that you may not be able to kill until you have the right spells / items, and tons of hazards in every stage. What makes it unpleasant is that you can just walk to your death at any moment by steeping onto a river, a hole, or a cliff in the dark... torches don't actually work, so areas with darkness are going to murder you about three-dozen times before you learn them by trial and error. That's not an exaggeration, either.
I did mention the art, assets and sex are all top-notch. It's kind of like Monster Girl Quest except the art in Siluman is markedly better and that's an achievement. But here's the problem: any time you have sex, you lose your balls. You also lose your balls any time you die for any reason. That's mitigated by using a 'Golden Balls' item to restore your balls at Lustfires (bonfires) but nevertheless adds nothing but tedium to the game. You can run out of balls and they're expensive to buy. You start out with a few pairs, but the gameplay is crippling and holds back the game itself, as you cannot avoid dying and you will not have the 'sex credits' to actually enjoy the sex-scenes if you are playing without cheating or skipping the game.
The combat is bad because it works on a rock-paper-scissors mechanic. Just like in Dark Souls... we have Sorceries, Pyromancies and Miracles. I didn't recall finding any Hexes but that's fine. You can also use archery or melee damage. But, here's the thing: there are a LOT of enemies immune to multiple types of damage, and it takes some time and hard work to actually have access to all damage types. That means some enemies you run into can't be defeated, and some of these you can't run from either: you can lose all your 'sex-credits' (balls) for no reason other than that you were caught in the long early-game by a monster immune to your damage. And there's a lot of these monsters!
But here's the worst thing: the 'golden balls', your hentai credits, whatever you want to call them... the whole dynamic of losing them if you're bad at the game can be completely mitigated by just one flaw in the game's design: you can save-scum! Just save often, reload any time you die / lose balls and then try again. All you lose then is time. This seems to be the best way to play, saving-up your balls and save-scumming them all the way until you're at a place you want to spend all your sex-credits. You're not going to enjoy this part for more than about ten minutes though, whereas you'll work hours just to get there.
Basically... the game tries to use Dark Souls mechanics, plus the general harsh gameplay style of the franchise, but it becomes a needlessly tedious rock-paper-scissors RPG where you will needlessly die many times to reach a comparatively (very) small and short-lived reward. But, the game does have potential, and the art plus the girls themselves are all great.
Overall: 4.5/10, performs poorer than similar RPG-maker porn games despite employing fantastic assets (art, scenes, writing)
Siluman: You need to rebalance this game. Here's some suggestions-
+ Remove immunity from most of the game's enemies so they can be fought, like the ghost skulls.
+ Don't remove the player's balls when they fall off cliffs / drown in water.
+ Make the torches work! The Black Slit is needlessly painful.
+ Don't let players access that magic mansion thing with all the h-scenes until they've beaten the game.
+ Make golden balls in the Lustkeeper's shop cheaper...