a manhwa just popped in mah head and i forgot it's title, help meಥ‿ಥ

so the ml there is an office worker(?) and then there this novel he was reading for 10 years(?) at first many were reading the novel but as times goes by he was the only one left. Then, came the day wherein the last chapter arrived. The author gave a file to the ml as a gift for reading the novel until it's last chap. He was then in a train unexpectedly with a girl co-worker, they talked and after a while, chaos happened and a monster from the novel he was reading appeared and gave them a mission to kill a living being or they'll die. Some pips where killing each other(?) The ml thought of some idea because it wasn't said that they should kill a human but just living thing/being(he shouted at this part) then here was this kid who was holding a bag of insects and the ml killed some, gave the kid and his co-worker an insect too, there were insects left so he throws it away to the other pips then BAAM the time limit ended. The others were dead leaving just 5 persons, the ml, the girl, the kid, the soldier and a greedy fucker from the company of the ml.

it started like this so if ever someone knows please reply, it's been bugging me really(╥﹏╥)