I'm not as vindictive as you, but yeah, it's disappointing.
For me, the biggest issue is the combats. It becomes really hard really quick and not because it's well done with strategy and smart difficulty but because the enemies are too powerful. When an enemy can hit you for half your life everytime, it's just frustrating and even with the magic to raise the def, it's still too much and you spend your time between healing and raise the def and sometimes you can hit back... It's not a real RPG and players are doing it for the story more than anything else. I understand that adding combats helps to extend the length of the game, but they don't have to make it that hard. Even the old Dragon Quest are very easy compared to this
The story is... ok. It's not really a mother sister NTR since the MC is not related to them (his parents died long ago and his neighbors took care of him). He's secretly in love with the girl who acts as his older sister but she doesn't notice and of course she gets corrupted. The mother of the girl is also NTRed but it feels more like the dev put it just to add more scenes. It makes sense for the story but it's badly integrated. Like I said earlier, D.P. is a better game than 黒き胎動. Not a terrible game (I bought this one and clearly it's a lot worse...), but it has too many flaws.
