Recommendations

Seconding the ONHCT rec - these are both Taiwanese dramas with a supernatural story. There are elements of Chinese myths throughout. Both dramas involve reluctant but decisive MLs, who have simple souls but also very strong moral compassess. In both cases, the plot is strong and the special effects are good and support the story.

It looks like if SK has the knack of horror dramas, Taiwan is sure getting ahead when it's about supernatural.

Both shows show a case of an individual loosing their mind living at a Goshiwon (Residency). In Trigger, this only applies to the first criminal case in the show (roughly 2-3 episodes), whilst Strangers from Hell delves into this storyline as a whole.

During this time, both MCs in that case share the same values, emotional outbursts and mental instability. Both MCs have an influencing figure grooming them into commiting criminal acts.

Both shows tackle the subject of preventing or succumbing of these sociopathic tendencies to kill others. Trigger focuses more on the preventing side whilst Strangers of Hell focuses on succuming to that nature. Both shows are quite alike, crime, thriller and psychological. Two sides of the same coin.

Sci-fi comedic mysteries.
Both about female lead being coworkers with an alien.
Hotel business vs kitchen setting.

The core concept of both series involves communication between characters from different points in time. In Kairos, the male protagonist lived three months ahead of the female lead, using a cell phone for their interactions. Time Rescue follows a comparable storyline, but with a time gap of 12 days, utilizing a lantern for their exchanges.

Both FLs are powerful and immortal, MLs are human. Both SMLs have a long time obsessive love for the FL. Both are xianxias with a similar vibe.

Similar with the investigations, addresses sensitive topics, and they are centred around justice for the people who can't get justice for themselves, ghosts and probono cases, they all deal with one case per 2 episodes ish

Mad Concrete Dreams, Dream Life of Mr Kim, Walking on Thin Ice, etc - so many dramas about ordinary people resorting to illegal activities to "win" in the rat race - are just variants on Squid Games season 1. (Seasons 2 and 3 are trash), Season 1 is a "molotov coctail thrown to expose exploitation by elites" as one reviewers so well described it. Imo they are also a molotov coctails thrown to expose how the flaws and dumbness of ordinary people lead them to be pions and exploited by the elites.
So if you want to watch the most violent deep-source, root-causes version of MCD, then watch Squid Games season 1.

Both seem to be adapted from the same script so it follows the same storyline. A down and out heiress in debt hooks up with her cheating fiancé's uncle.

If you're interested in Park Gyu Young in another romantic lead , with a different flavor to Fall in Love, I recommend Dali & the Cocky Prince. Quirky and fresh, her character was softer, with more frills... And you get to see her range.

Both MLs are depressed and at the lowest part of their lives when they encounter the FL who they view as their salvation. Both MLs become stalkers, finding ways to get close to the FL, with her having no knowledge of their shared past/former meeting.

Literally the same story! I think they stole the story. Both are about people who accidentally time travel to the same old era in the past. They both have to adapt to their life in the past and they fall in love with the hot guy who works for them. Both from a royal family and a forbidden BL romance. Both have a comedic ML and there's funny moments.

The 2nd couple is similar (2nd ML: Stoic, 2nd FML: a little sunshine) -- The 2nd ML keeps denying it at first and see himself not worthy for her

Both os these BL dramas are almost practically the same. I will say Make it Right has less of the 'ashamed to admit to being gay' theme to it that saturated Love Sick, but I liked the plot of Love Sick more as it felt more reality based while MIR felt more like a drama.

Romcoms.
Main character has memory loss, and is falsely told that they're married and a parent by other MC for selfish reasons. Leads then live with eachother under these pretenses.
When the truth comes out, all is forgiven.

Both Eternal Yesterday and Contrast are serious Japanese BLs where the popular guy is drawn to the loner.