Forgive my ignorance, But the MC's mom is dead. And there is no mention of a sibling.
So without spoiling, how does the incest fit in the game?
Confirming that it fits in neatly will be enough for me if you can not provide an answer without spoiling it.
I always try to play a game as the dev intends it to be (If it were not for Patreon). I hate Landlady, Best friend from Childhood (Staying in your house) and other contrived type of shit. But the incest should provide some plot point or social taboo.
There is no stigma/plot point IMO in fucking your Landlady or some chilhdood friend that happens to stay in the same house.
While the game can be played without incest and its quite good, the incest elevates it to a new level, I cant believe people who sometimes are quick to condemn anyone that doesnt feel "progressive enough" to enjoy trans or other fetishes are quick to denounce incest in FICTION...
First of all the game is called "No more SECRETS !!!" meaning the MC is sick of all the secrets going on in his life, based on his backstory, and what happened to his "parents" you'd think that'd be the big secret, but the patch clearly shows its NOT, there is one more massive secret he still has to uncover.
Second... the way Lizie acts... no fucking way a "roommate" or even a step-sibling that only met her "brother" once they were around 16 years old is gonna be that against fucking him !! There is attraction from both sides, and the MC has no problem trying to get into her panties, she however sees it as sinful and gross, why is that ? What secret could she be hiding ?