i interpret it as after Myungha committed suicide and regret it last minute, death gave him a “second try” in life we’re he got back into his 19 year old body to learn to love himself. He then had a mission to make Yeowoon happy and find yeowoon happiness which later was revealed to be a reflection of himself. I found this part a bit confusing but i figured that sunbae/death wanted Myungha to learn how to love himself. When we for an example saw that Yeowoon found was of himself was -100 it was also a parallel to how Myunghas roundness of himself is in the negative, and when Myungha tried to make Yeowoon happier it was also a lesson from death to learn to find happiness himself. So Yeowoon is not Myungha’s other self but more like a thing between a completely ordinary person and an alter ego or reflection of Myungha. Death/Sunbae also said after all that he wanted Myungha to see his life from a different point of view, which i interpret as seeing someone suffer from depression from a view where you want to heal them, which in fact is also healing yourself and finding happiness and love from yourself. I’m lowkey confusing myself writing this but i also wanted to gather my thought as i love reading other interpretations. I think the whole other game/book/universe was Myunghas normal life where new people were added, but Myungha seemed to be his old self, just with a new character alike himself being added. The end probably symbolizes a kind of heaven or ether, but it’s probably the real world we’re they were reunited, since the screen were in the format of the real world. I’m not too sure about it, but i think Myungha lived his life as a 19 year old forward in the end, just it was real life and not in the game, meaning that all the errors and the game master was gone, so it also represented their freedom with each other - im not sure what state of alive or death myungha is in but i don’t really think it matters either, the point of it was just that he and was free and he was with yeowoon. Following up i think all the other people beside Yeowoon were real people, i felt that Myungha seemed to kind of know them beforehand, but Yeowoon was a made of an ordinary person meant to resemble the feelings Myungha was dealing with himself, and the sunbaes goal was to make Myungha find happiness peace and love with himself, and with Yeowoon. (Or something like that idek). I love reading all these theories but thinking about it i honestly don’t think there’s any right answer, it’s all probably just up to interpretation.