They both have a cast of unique characters solving a mystery in a location they can’t escape from. They also both start out somewhat slowly before delving into a story with plot twists and intrigue

Tony Yang and King Chin are in both of these, and they’re both about gay characters. However, they’re pretty different in tone, Formula 17 is pretty fun and lightheaded while Crystal Boys is way more serious.

Both are short BL shows with main character(s) associated with gangsters. While red balloon differs in that the main characters are teens for most of the story, and it’s less intense than long time no see, both have very heartwarming and convincing relationships between the main characters, and interesting side characters.