Well, we made it fellow reset-fans! The ending of a great mystery series with tons of theories involved. It's been fun trying to find the reason for their deaths and the secrets of Lee Shin. 

Some of my favourite fan-theories were: The group is asleep in an experiment, the group are experiencing the afterlife and that Maru is the key to resetting. 

I loved this series music-score, the overall aesthetic of the environments and the imagery of certain scenes. I also liked Ga Hyun and Hyung Joo a lot as characters. Ga Hyun started off unsure of who to trust but grew as major support of Hyung Joo. Detective Hyung Joo just had such a sad backstory that you couldn't help but feel sorry for him as he fell deeper and deeper into his selfmade trap. 

Now that the ending has happened. What was the yellow car about? 

 RandamUsagi:

Well, we made it fellow reset-fans! The ending of a great mystery series with tons of theories involved. It's been fun trying to find the reason for their deaths and the secrets of Lee Shin. 

Some of my favourite fan-theories were: The group is asleep in an experiment, the group are experiencing the afterlife and that Maru is the key to resetting. 

I loved this series music-score, the overall aesthetic of the environments and the imagery of certain scenes. I also liked Ga Hyun and Hyung Joo a lot as characters. Ga Hyun started off unsure of who to trust but grew as major support of Hyung Joo. Detective Hyung Joo just had such a sad backstory that you couldn't help but feel sorry for him as he fell deeper and deeper into his selfmade trap. 

Now that the ending has happened. What was the yellow car about? 

Since he was the one who originally started resetting, I'd think if everything goes back to default, the Prof would make the same choices and end up at the same forked road and reset again. 

Theory 2: I think that since the prof wasn't really dead, just in jail, it's possible that he let the way to reset slip to someone else or someone found it on their own. Since Sun Ho got caught, all the original reseters should still be alive and can therefore also happen upon the opportunity.  Out of the reseters the Gamer is the one who's most one to be in the yellow car. His life is the most fucked beyond belief, admittedly due to his own actions, therefore he's the most likely to try and kill himself. Also, he's the only one who'd drive a car like that.

I loved the series but I don't want a sequel. Unless they can come up with a plot just as well put together with the same level of insane twists, I don't want it. I'm happy just rewatching and marvelling over this masterpiece. 

I think the yellow car means they'll never break out of that cycle of repetition, they'll be stuck in 2019 forever, every time you think it's over, someone resets again causing everything to go back to the zero point.

Can you blame them though? I'd reset forever too with how 2020 has been turning out. 

But yeah it might be an inescapable cycle but it's not like anyone besides the persons involved would notice and be bothered by it. 

I felt the ending was poignant. Sure, LJH's character went through another reset and saved NJH's character. But going by theories of how parallel universes and time travel work in the universe, there are multiple timelines where Shin Ga Hyung remains dead, along with all the other reset participants. And, out of all the other timelines created, only one existed where the main protagonist was alive. It was definitely bittersweet when Ji Hyung Joo went beyond his efforts to revive his partner and create a new timeline, but I can't get the idea out of my head that the characters I've grown so fondly met such tragic fates multiple times in different universes, and there is nothing that could reverse that.

 Jojo:
theories of how parallel universes and time travel work

Yeah this is definitely true. There's a lot of dead resetters in other timelines, either at the bottom of that cliff or just killed. In my opinion though, a resetter with a surviving conciousness was needed to stop the cycle. If detective Hyung Joo didn't make a final reset then the cycle may have continued many more times (lot more deaths). Him and Ga Hyun would've had to suffer many more times and while they wouldn't have known, it's still not a pleasant thought. 

Someone had to make a final sacrifice to live with the 2 years of different-timeline memories. Yes, I would call this a sacrifice because of the trauma. I had hoped this would've been Ga Hyun since the detective Hyung Joo would've benefitted a lot more from losing his reset-conciousness. Sure the betrayal of Sun Ho would've been a surprise to him but it's better than what he went through in the 2 previous timelines.  

I also kinda hoped the drama would've taken this route of claiming that they had already been resetting thousands of times. That would've made the scale a lot more impressive and could've added to the villains character as he's been carrying all those timeline-years of conciousness. He could've learned everything about them as a person with that many timelines and that would've been a bit scarier. I know this would've forced the showmakers to explain why this timeline it was different but I'm sure they could come up with something. 

I have a theory: what if she and her daughter died on that train? The train that was derailed and killed 2 people, that part was mentioned on the first episode. At the final episode, She chose not to go back in time (reset) so she can spend time with her daughter and promised her to ride the train together, what if that train was derailed and they are the 2 people that were killed?

If that’s the case, well, that’s terrible. What if she finds out that both of them will die in a train derailment if she chooses not to reset? Will she reset and make sure she avoids going to the train with her on that day?

Because at the final episode, the train derailment didn’t happen... yet. And it shows both of them are on the train so we don’t know whether if that’s the train that will derail and kill both of them or they are on a different train.