I feel like everything has been said already, but to me, the most anti-climatic tropes are:
Of course, I'm exaggerating for comical effect, and when those tropes are played straight, it can be quite enjoyable, but come on guys, lay off making the same bland incest games all the time.
- Badly written incest: MC's
momlandlady lusting for her son's cock after having seen a morning wood once. As Avaron said rightly, the woman has been jumping on dicks for years, there's no way she would hunger for her own son's noodle. MC'sauntneighbour being generally a depraved ex-model or ex-porn star that wants only one thing: teaching her nephew how to do the Moldavian wheelbarrow. Sex teacher = good, same old rehashed model milfy short-haired aunt = boring. And don't get me started with the MC'ssistersroommates. Fortunately, games like "My sister, my roommate" (yeah, if irony were chocolate, I'd be getting diabetes right now) play the trope right. - What really grind my gears, though, is the trope where sex just appears out of the blue: "Hello, I've just met you, and this is crazy, but here's my member, so suck me maybe". I mean, I understand that these game are porn related, but by jingo, can't we just have a little interaction to care about the lady? Games that put badly scripted unoriginal sex scenes without reason right at the beginning as a hook tend to end in the trash bin.
- Also, I don't know if it's really a porn game trope, but it might as well be: if engrish be to strnog, I generally don't bother. Lot of people here are not native English speakers, and that's alright, neither am I. But at least make an effort when releasing something that calls itself a "novel". This one is quite sad, because sometimes the renders are really neat in the preview, but everything is wasted on the first few lines.
- Which brings me to the last anti-climatic trope I can think of right now: unoriginal setting/scenario. Once again, I understand that we're not here to read the next *insert here a book you like*, but the same school settings, the same old scenario where you're playing a young student down on his luck, the same unoriginal ideas that make every game the copy of a copy of a copy of Big Brother... It gets tedious. Personally, when I play a visual fucking novel, I like to put emphasis on the "novel" part. It doesn't have to be perfect, but at least interesting characters and stakes are a minimum. Watching characters having sex when you're not involved at all, it does nothing to me.