So for me, the biggest's no no omg no never in my entire life i will touch this kind of games are:
-Is first, the Japanese octopus problem know as "tentacle-chan getting all the girls", in general those games are ever super retarded in there conception ( go their, do that, grind the shit out of the 3 same different monster that you will found at every stage of the game) , or you need to loose battle on purpose to have access to the lewd content, and they all look the same, i mean how hard it is for japanese to not put tentacle in every game they made, for real what is wrong with these ppl lol.
I mean, at this point a big part of the japanese culture in itself is so crazy, so many example, im giving one that totaly destroy my brain recently, schools checking the color of the pantys of underage girls ( yeah i know they stop it in 2015, but the simple fact that rules like that was created in the first place, literaly mean they had some completly retarded pedo wanting to have their low lvl fetish easily accessible and ppl actually voting for them.... ) and so much more nonsensical things that i won't talk here since its not the subject in itself.
But a lot of those fetish and retarded behaviour find there ways in lewd video games or manga etc..
-The second one, is furry, or zoophilia but with humanoid form. Not gonna explain why i hate this content, since i consider it zoophilia.
-Third one is scat, not gonna explain why because it's pretty obvious.
-HTML "games" that are 99% text, i don't consider text based games are actual games since there is literaly no gameplay whatsoever. It's a book where you can make you'r own choice but not a game.
-I can accept some gays scene ( male/male) in games, if its related to the story, or just a few scenes it does not make me instantly quit the game. If it's 100% gay, i'm not playing it.
-Futa forced content. At least if in most of them it was explain like in "Succubus contract" that the dude or the girl will swap gender, i will be ok with it. But both sex in same times, or suddenly growing a dick, just make me instantly quit the game. No matter if the story is good or not, it's not like 99% of the games in here don't have a good story or even jokes inside of them to begin with.. But in contrast i can accept futa content if its like a trap content where every character knows that the mc have female attribute while having a dick, but the narration or story telling need to be really good, which is never the case.
And i think its all for me. Maybe a few more that i can talk about but there are irrelevant since the forum already have rules about loli stuff etc..
