Circle (2017)

gripping, complex & full of dark and futuristic themes, both of these dramas are absolute must-watches, particularly if you want to watch something special & unlike many other dramas
>> the execution of the dimension-switching in train is highly convincing, plus very reminiscent of the divided timelines in circle
>> similar overall vibes (although train is more supernatural? vs circle's scifi)
>> both focus heavily on investigations
>> the male leads suffer traumatic losses, dedicate their lives to protecting their loved ones & uncover some nasty truths along the way
>> ...with a side of thought-provoking (and often mind-blowing) moral/ethical issues caused by messing with fate (train) and memories (circle), and how these can butterfly effect to drastic proportions.

While Chicago Typewriter is more historical fiction and Circle is sci-fi, both shows present two stories in one (in Chicago Typewriter it is past and present day, while Circle is present day and future).
In both shows, there is a mystery that happened in the past that the future is trying to figure out. And in both, the viewer is (for the most part) unsure what exactly happened in the past, and everybody's role in it, until it gets revealed.
They both also play with memories.

However, they are still different as they are in different genres and there is a larger time gap in Chicago Typewriter than in Circle. The sequences are not as ordered in Chicago Typewriter as they are in Circle, however the transitions are incredibly smooth.

Bonuses:
- I really liked both the female leads
- Great acting
- The bromances ^.^