The first 80 chapters are probably as good as the manga gets. With the world slowly unravelling itself, new characters are being introduced while still struggling to survive. It felt it could've been a very special manga within the survival game genre. You are filled with questions and excitement towards the future of the series.
Unfortunately, you will soon realize all the characters are one-dimensional and severely lacking in character development. None of them will grow in any substantial ways in the next 100 to 150 chapters.
Characters only make up half of a story, so let's look at the main plot: it's not that much better. I won't go into any spoilers but know the main conflict isn't all that bad until the last 1/3. The dramas are fairly interesting and there are some good dialogues. But the plot took a nosedive after the death of the boss. The main villain reveals himself and he isn't even a character. There was no build-up, no foreshadowing, and his existence makes barely any sense.
Speaking of which, let's talk about setting. Remember how you had all those questions about the world, well you do get some answers, but they are so conflicted and meaningless that it will only leave you scratching your head more.
All good survival game series have one thing in common: high stakes. Because in order to make the readers care, you have to give them a reason to. That's why the characters are often in a disadvantaged position with a high penalty for losing, ie dying. However, when characters can one-shot any enemies they encounter, there is no more tension.
One of the ways to solve this problem is to introduce more powerful enemies, which is what the series did. Yet the power-scaling racked up so fast that the writers themselves couldn't control it and quickly spiralled out of control.
A short-term manga requires talent, but a long-term manga requires commitment and planning. To me, this manga lacked in the planning aspect. With plenty of unfulfilled potentials. If you want something similar to this, Btoom or battle royale are all better than this.
