4.
This one is a hidden problem that was kept from all the beta testers but two outside of the one group that is aware of it, because it forms directly from their area, exactly. After the reveal of the nine demons, there was something that happened. It was not announced to any player or any demon at all. It was an instantaneous event that happened that did not allow for anyone to become aware of it until much later. Even then, it was only two players from the outside that became aware of it. That being said, there were ten areas, yet only nine of them had a demon of their own to deal with. The first nine starting areas had an equal amount of space from each other. However, that was not the case for the tenth area, which was ten times the amount of space for any other starting area in all directions, as well as located on a massive island in the dead center of a massive inland sea. This was also reflected in how their area of the facility was located within 'reality' as well. It was so much that the tenth starting area was hidden from the others, more so that they were not told where they exactly were in either layer of The Decagon.
There was no form of conventional fast travel in The Decagon, nor any form of traditional chat or PM feature either. If players wanted to talk to someone, they had to meet them directly, otherwise they were not talking to or interacting with anyone. The system that seemed to be a global setup was the one that informed them all of the true nature of The Decagon and the purpose of the game itself. One could travel from one area to another, but it was not going to be that easy, as just because there were no NPCs did not mean there were no dangers in their world. The environment itself was the danger, as numerous different biomes existed inside of the game world. Each starting area was located in the dead center of one that was each unique to them, and each posed its own challenge in getting around in to venture to another one.
The same problem was present when going between different facilities as well. One could walk between one and the other, but the hallway that led to them was as long as the distance between the starting area inside of the game world. With the surrounding outside area being twice the overall distance, even more for the tenth area. This leads to why no one at first would be aware of what happened to the tenth area. When the announcement of the nine demons was made, there was something else that happened beyond that that was not made known to those who were within the game, again, beyond those to whom it happened to.
The ten starting areas vanished seemingly from the face of the game world, replaced by a massively dark pit that was so deep that one could not see the bottom of. However, what happened to the tenth area was not that it vanished; it was instead relocated to the very bottom of that massively dark pit. This was The Decagon's version of a hidden super dungeon, after all, as they had superbosses, so why not a hidden super dungeon as well? One that existence had to be discovered by those of this world... except for those that are trapped at the very bottom. This served two purposes: the first would be eventually revealed, but the second would remain hidden even after the discovery of the first one.
The first being that this hidden super dungeon was not made for the players at all; instead, it was made for the demons primarily. This dungeon was the only place in The Decagon where the rules were reversed, as a demon that entered into this dungeon. They would always do so with their full HP (thus they would have one trillion HP) once entering, regardless of what it was currently at the moment in outside of it. Also, if they were to die in this dungeon, then they would not be dead for real; instead, they would be kicked out of the dungeon itself. Their HP reverting back to its original amount that was before they entered it. Though that should seem like a cakewalk dungeon, as they were maxed out in everything after all.
That would normally be the case; however, since this dungeon was literally for them, everything within it was set so that there were basically the equivalent of level one the moment they entered into the dungeon. It was full of unrelated and unforgiving traps, pitfalls, and other devices made with the demons in mind. They were also not restricted to only use their player, demon, or massive kaiju forms either. All were fair game within this dungeon, but everything scaled, thus it was the only place in the game where they were the weakest once again. Since the starting point is the max level for square one, that probably causes one to think that the next level can not go higher. However, that is where they would be wrong, as the level increases every single time by one. There is an unknown number of levels, with the bottom itself being unknown. However, the reasoning for a demon to venture to the bottom is that there is a hidden win condition to the finishing the game that does not result in all the players or all the demons being killed. It is one where the demons make it to the bottom of the this massive super dungeon, and they take out the tenth demon themselves. That being if they take out the system, being it can be awakened, then all the players, both player and demon, all remaining players would be allowed to live.
Although there are a thousand players trapped at the bottom of this hidden super dungeon. If the rules of The Decagon are reversed within it. That actually means that the players of the tenth starting area, if they were to die, they would die for real. There was no coming back for them, and what makes it worse is that if they were to become a Player Killer, then they were banished from the one safe zone within the hidden dungeon. Those who left the starting area to settle down in areas outside of the starting area, they were around for that much longer, as those areas became a part of the hidden super dungeon itself. Making sure that the remaining nine thousand and nine beta testers were unaware of what they were going through. Of the two beta testers, one would become aware of this hidden super dungeon and its purpose much later on. Only one of them would know about the players trapped at the bottom, and they were keeping hidden for good reasons by this point from the other beta tester.