Signal

These dramas offer intense storytelling, complex characters, and themes of crime, morality, and personal struggle, making them excellent choices for fans awaiting "As You Stood By."

Both dramas deal with a mysterious storyline with a great ensemble cast and acting. The stories are top notch and effectively delve into various genres while settling with the main story idea. Writing is phenomenal and cinematography is somewhat similar because of the tones the two dramas carry. Actors really excel in their work and transport you to the scene of the situation.

Both male leads are in contact with someone from the past and exchange pieces of information with each other through a specific machine. The big difference between these two is that they have completely different genres. Signal has little to no romance and focuses more on mystery suspense and crime while ditto focuses more on romance. Signal IMO is an outstanding drama, please do watch it if you have time.

Both the shows have Lee Je Hoon as the male lead being his usual clueless yet loveable self, meddling with different time zones while trying to solve the murder(s) of a close acquaintance.

Fifteen years ago, a young girl was kidnapped on the way from school, and Park Hae Yeong, who was an elementary school student at that time, witnessed the crime. A few days later, the girl was found dead, and the police were not able to find the culprit. As time went by, Hae Yeong started distrusting the police. Fifteen years later, Hae Yeong is now a police officer and criminal profiler. One day, he finds a walkie-talkie that allows him to get in contact with Detective Lee Jae Han who is in the past. Police officers Hae Yeong, Jae Han, and Cha Soo Hyun then set out on a journey to solve cold cases.

Both dramas have a fantasy element that fate can be changed. But for worse or better? Can changing the past somehow lead to a different future?

Just like The Game, Signal deals about murder cases and supernatural occurrences that help investigation teams solve them. While Signal does this with a walkie-talkie that connects the present to the past, The Game deals about someone who can see the death of people. Both try to solve cases with their unique ability. Also both resolve around cases that shape each main character. the cases that shape them are quite similar to one another as well however due to spoilers i cannot go deeper into this.
Signal is a masterpiece of masterpieces, The Game seems to go into a similar direction with it as well.

Both establish communication with the past with a device. I think the first one was the movie Frequancy (2000).

This recommendation should provide you with thrilling narratives and complex characters reminiscent of the themes explored in "The Price of Confession."

The main serial case in both dramas have a lot of similarities, in which it may be based on the same murder case that sparked many different dramas and movies based on it. In both dramas there seem to be some hidden conspiracy which lead to people attempting to cover up the murder cases and led them remained unsolved.

Here are some common points between the two

1. Communication across time
2. The past can change the present
3. Mysteries that need to be unravelled
4. Characters haunted by the past
5. Cooperation between people separated by time
6. Suspense built around consequences
7. Emotional stakes beyond solving the mystery

although the guest is more about demons and possession, and signal is more about time slips(?), they both have similarities in terms of the main three working together to solve various crimes. they both also have similar mature / dark vibes with heavy themes.

Duo solving crimes together, often at odds due to their differing methodology (one follows rules but still tenacious and the other jumps straight into action without thinking things through).

Why Similar: Signal combines crime thriller elements with a complex narrative involving secret investigations and mysterious events. The show also features an intriguing storyline with twists and turns.
Plot: Detectives from different time periods communicate through a mysterious walkie-talkie to solve cold cases and prevent crimes.

Both dramas are about profiling.
Both are taking place in various time zones starting from the 80ties to the 2000s.
Both are thrillers with interesting cases. Both form teams that specialize in this.
And both have a male lead that is shaped due to his childhood and is doing a sort of narrative analysis's throughout the episodes.