First off, the titular gimmick: the No, Thank You!!! button:
While the game does employ traditional text choices like these as well (they’re generally route-determining choices of who you opt to spend time with):
The game’s main gimmick is the No, Thank You!!! button. Basically, this button will pop up in the upper left-hand corner of the game screen––like this:
––whenever you trigger a ‘flag’ (a basic game mechanic for most visual novels and many other types of games, I guess you could think of a flag as a prerequisite for an event or ending). If you click the button, you can destroy the flag that’s just been triggered. You can also opt to ignore the button and leave the flag standing. Functionally, the NTY button is more or less equivalent to a traditional two-option text choice, but the unique thing about it is that the game doesn’t explicitly tell you what the decision is, you have to intuit from the situation what you’re saying ‘no, thank you’ to.
But don’t worry! If you get really stuck trying to get all the endings, once you get through a route once (with any ending), you have the option to turn ‘hint mode‘ on and the NTY button graphics will change to tell you what the correct choices are (the hints also give you a little more insight into what Haru’s thinking).
One of the game’s other unique features is the body hair options! Yes, that’s right, you can decide how much body hair you want displayed on each guy:
You might notice that not all of the characters have the same hair options, well, that’s because not all the characters are equally hairy. Ryu and Haru in this case only have pubic hair, so there’s no point in making it a separate option. The options affect both how sprites are displayed:
And how CGs are displayed:
However, it should be noted that it’s exclusively a visual option. The text doesn’t change and Haru does make a few references to body hair on occasion (there’s actually a shaving scene in one route that ends up looking pretty silly if you have all the hair turned off!). The body hair options have no effect on the story, so feel free to set it up to your liking! (You can change it up at any point in the game too.)
You might have also noticed on that screen that there’s not one, but three voice sliders for each character. What are “BG Vocals” and “BGF Vocals” you ask? Well, while it’s a common feature in traditional eroge, as far as I know NTY is the only BL game to have it: looping background vocals during h-scenes. “BG Vocals” are general breathing and moaning and “BGF Vocals” are the sucking and slurping sounds (made by the voice actors) used in fellatio scenes.
For example, here’s one of Hiroyuki’s BG Vocal tracks:
And here’s a BGF Vocal track from Kouichi (yes, even him):
Check out the demo to get a better idea of what the effect sounds like in context (Hiroyuki’s scene is probably the best example).
The game also has a nifty little feature called ‘Voice Collection’ which allows you to save your favorite (voiced) lines to listen to again later: