This does, fully and to great effect, what it says on the tin: it's a tentacle rape and mindbreak simulator.
There is about 20min of "gameplay" until you have unlocked all the options and statuses, and I don't think there is a lot of repeatability in it, but... there you have it: a humble mission, fully accomplished.
While the term "game mechanics" may seem a bit too grand for what this is, it's appropriate for this game: the combination of simple systems is more than the sum of its part. It's intuitive, works well, and doesn't leave much that could be added within this narrow simulator scope.
The graphics are excellent, fluid, and highly customizable. 3 pages of customizations options for the character, the tentacles, and the action may seem a bit much, but it's actually easy to figure out, too.
And the voice acting is great, not overly "japanese hentai", and adjusts to the game situation quite well. One could just wish to have a choice for other tones of voice, but that is a very minor wish here.