It has its potential for what it is, being a rather simple game, but with slow updates (at no fault of the developer(s), I'm sure they are doing what they can with a lack of financial support) the game has not really progressed far enough to see whether that potential is truly there or not. As of this review of v0.1.3, you finish the game's current version in twenty minutes, give or take your reading the dialogue.
I initially downloaded the game because it was tagged as 'female domination.' This was an exciting idea because the artwork depicts some rather appealing female characters, but there wasn't really any female domination. The closest it gets is losing a riddle challenge when meeting a new character during your third "quest." I use the word quest lightly, because quest implies some type of journey or progression whereas here, it's just talking to the NPCs around the succubus queen's castle to see if they have a task for you > click on another part of the map > basically quest finished. There's no real challenge to it, and you can tell the entire idea is to just show off the artwork and animations. I just question how long the development team can keep it fresh enough in lieu of actual gameplay or plot and character development before it starts to appear repetitive, as most of the sex scenes so far are oral receiving, paizuri or vaginal with some buttons that you can click to add toys or change the female's clothing, etc.
Mostly, it's so far closer to male domination because the male character seems more aggressively natured, or it might be something more similar to a harem game where all the girls fall in love with you because your character has never-ending sexual stamina.
The game's story portrays the usual "angels versus demon" plotline that is rather common for these adult games. Your character is forcibly aligned with the demonkind upon finding himself in a castle during the prologue., 'else he is killed by the succubus queen should he reject her offer.
Looking at other Pinky Pads games, they seem to develop games that are short and simple. Their Twitter page states they want to someday turn the game into an "epic adventure" and I certainly hope they find the success to do that, but everything in the game seems to progress very quickly to be counterintuitive to an epic adventure. There's no buildup or getting to learn anything about the characters you are interacting with. With how the game is developed, it plays similarly to other games like Seeds of Chaos and while I failed to enjoy that game because it's too much gameplay and not enough sexual content, I would say that game is more akin to an "epic adventure." I think it's important to try and balance the two aspects of storytelling and porn otherwise you are going to have a game that is finished quickly due to lacking in story and dialogue, or you are going to have a game that gets boring because it forgets the pornography.
With the quality artwork and animations and what is essentially collecting a harem of ladies, I feel like the game could have been better designed as a "battle fuck." Fundamentally, it's more linear and almost more like a visual novel, minus the novel because there truly isn't that much dialogue before you do get to the sex scenes. Which I personally think is a good thing, although dialogue is still important. But, I wonder if the foundation is really there for it to actually be an adventure, yet alone an epic one.
When I think of the developer's sight to create something like an epic adventure, I think of a game with some complexity to its systems. Some elements that would give it replayability. Developing relationships with characters over time, stuff of that nature. There's plenty opportunity for that in Succulust if Pinky Pads wills it to be.
Either way, the plot isn't developed enough to really judge if it is unique or not but the artwork is definitely high quality and it has good animations.
Good luck to Pinky Pads. I'll keep playing the new updates as they release.