Guys! I just had a genre idea, which I will call it "Dark isekai" which I will be focusing right now, or maybe not.
It is a combination of Isekai, cosmic horror, dark fantasy, grimdark and sometimes scifi.
About "Dark isekai": It has a main theme of death, dread, danger, madness, hopelessness, and helplessness.
The MC is either forced to do or is willing to do such disturbing acts which necessarily connotes death.
The setting of this genre is either a typical fantasy world or a different world where danger and dread is a norm(Ex. Hell-like place full of malevolent creatures, a strange place where the MC is being hunted by enemies in anytime and anywhere, a backrooms-like world/balikrooms, or simply a literal "dungeon world").
Sometimes, the MC would have a ludricous goal trying to escape the world they are been sent to.
The ending usually has a sad, bad, or an ambiguous ending. And the ending bases on the MC's fate.