Recommendations

I felt that Run On depicts picturesque landscapes and somehow even One Spring Night gives off the same vibes when it comes to weather and landscapes.

Also, I really like the contrast in the dramas where Run On shows the beauty of the day especially the morning and One Spring Night makes the dark look pretty and somehow uplifting.

Both 'Haeundae Lovers (2012)' and 'Woman of 9.9 Billion (2019)' feature Kim Kang Woo and Cho Yeo Jung as the main leads.

It is helpful if you press the "Voice Actor" Tag, this is another cdrama that has a similar premise. The FL's profession has to do with voice acting and the couple connects through related work.

Gen Y has a combined cast of Superboy Project and SBFIVE. The main leads played by Kimmon (SBFIVE) and Copter(SBFIVE) have great on screen chemistry and the story for Gen Y focuses more on just the romance between the two main leads.

It has some of the members from the superboy project in it. It it short but sweet and Pon and Bank are the main leads

The main character in both movies had to confront with someone out of their league (in terms of fist fighting) for the sake of the woman they love. Both are adapted from "seinen manga" and good at portraying the anger and frustration of the main characters.

While the premises are very different, the feel of it was similar.

You have the "life back then" aspect of it; you get to experience how life was back in 1998 in Taiwan. You also have the family and friend aspect of it; you get to see the friendships developing and turning into more, as well as the relationship with the family improving. As well as the heartfelt feelings between the leads, the patience and the love.

That being said, 1988 is purely a "slice of life" drama vs. Someday also has a time travel element, as well as a murder mystery added to it.

Both of these dramas are excellent, and highly recommended.

The two male leads have the same dynamic in both dramas, where they're both fighting and the girl gets in the middle.

Their plot is very different but both the dramas have very healthy central relationships that are built out of mutual admiration, support and understanding. Main characters in both dramas are somewhat quirky and have distinct and likeable personalities. A bonus is that both do not involve love triangles.

Similar theme of girls going through ruthless preparation to avenge their closest ones. Great fighting scenes and gripping plot.

Main characters time-travelled to Joseon Dynasty from modern day. In MQ, he is a chef. In DJ, he is a doctor. They both used their own respective skills to help out people around them. They both were kinda entrepreneurs in Joseon.

I've only watched a part of First Love It's you, its giving me You Are So Sweet vibes. FLIY is VERY short though.
- both in the dubbing industry
- ML has "hidden identity"
- FL admires ML's hidden identity
- pretty light romance

I just realized these two dramas have similar vibes.
- Both are time-travel sageuk dramas
- Joseon Dynasty
- Beautiful Love Story and amazing lead couple
- Both male leads are tricked by second female leads and they thought SFLs are their childhood first loves but actually FLs are.

Both dramas are about younger woman/older man relationships,dramatic,awesome ,really well executed and beautiful .

It's set in around the same time, though in History of Crime there's no CCP and is more just crime-solving and mafia-ish vibes and in Sniper there's more elements of communist propaganda.
I find HoC and Sniper similar in that they both have this main theme of people coming together to solve crime despite having different backgrounds. There're also two main male leads (though HoC also has a FL lead who's actually quite a good character unlike the one in Sniper imo) who are friends, though in Sniper it's friends-turned-enemy and in HoC it's sortof-enemies-turned-friends. Sniper has hints of romance while HoC has none and is rather fast-paced in its development.
If you enjoy the combination of republican-era feel and crime, you'd likely enjoy both.