Started reading and dropped a few years ago. Male MC returns back to before the events happened with full knowledge of what's going to happen to the people on earth I believe it starts with people being transported in batches into a tutorial that was extremely hard I believe that the MC's tutorial had something to do with Seoul Station, so a Korean novel? I feel it had game elements I wanted to say the title was "Returner" or something with return in it, but that doesn't seem to be it. Ironically, reading through my list of things I can remember about the novel reminds me of how repetitive some of the plots are between novels. Not Seoul Station's Necromancer or The Tutorial Is Too Hard
Ohhh I’m pretty sure I know what you mean but it’s been a long time since I read it... what’s the name again...?