Tales of Undercrust was one of those games that fused the hentai aspects and the gameplay aspects in a way that you felt justified for PLAYING a hentai game. So many hentai games are just bad games with hentai cg, and so many others are just hentai with basically no reason for it to be a game.
This is 90% hentai and 10% a very basic action platformer, with many fixable flaws but some fatal flaws as well. You can tell there's been tons of effort put into it, but almost all of that effort feels like it's been put in the art/animations/overly elaborate debuffs that only contribute to the game in the most basic way of screwing with the struggle meter. The fatal flaw for me is a common one in 2d hentai action platformers; enemies are thrown together without rhyme or reason in levels that go on and on. Compare it to something like megaman where enemies and areas have purpose.
I'll still support the circle, but this is a game you blast through once, having to deliberately unlock the gallery as you go, and then you might open it once every now and then to look through the gallery with no desire to replay the levels.