It can be unlimited flow, survival, mystery, thriller, or horror. Even if it's not BL , a novel where the MC is a little bit of mental? Or have mental illness. Or have plot in mental hospital like that.
Here are some rec's: • https://www.novelupdates.com/series/thriller-trainee/ • https://www.novelupdates.com/series/thriller-tour-group/ • https://www.novelupdates.com/series/born-lunatic/
Idk if split personality or depression could be considered as the type of mental illness that you are looking for..... https://www.novelupdates.com/series/being-an-extra-actor-in-an-escape-game/ [Gong MC. Has depression] https://www.novelupdates.com/series/after-returning-from-the-infinite-game/ [Shou MC. Is taumatised] https://www.novelupdates.com/series/supernatural-movie-actor-app/ [Kind of split personality] https://www.novelupdates.com/series/phantom-skeleton-painting/ [Shou MC. Both are mentally ill] https://www.novelupdates.com/series/embers-ad-infinitum/ [No romance. Mentally ill MC] https://www.novelupdates.com/series/survivorship-bias/ [Shou MC. Dual personality(one is nice other is cruel and razy)] https://www.novelupdates.com/series/lord-of-the-mysteries/ [No romance] https://www.novelupdates.com/series/im-waiting-for-you-in-the-abyss/ [Shou MC. In a mental hospital] https://www.novelupdates.com/series/impersonated-husband/
Eccentric MCs (at least for me they're odd) Corpse Collector Welcome to the Nightmare Live Paintings of Terror Forces of Temptation
It's MTL so translation can be a bit whacky but "I Became a God in a Horror Game" is bl and the mc is like,,, so crazy for money it's basically a disorder on its own, and he also has some aspd/sociopathic traits and prob some ptsd too