@comeonnow0 Yea, why didn't the three main casts just defy Onodera who have goods of god? There's a reason why they're inclined to obey his word, just stop and think a little.
One way to keep him alive through this is by mean of Deus ex Machina, make him suddenly gain consciousness and return to the real world, for example.
But that would be stupid. Clearly there's some other way out
I think the number of shelters won't decrease to less than three... just a feeling I got when an announcer said "protect your partner from alien invasion". Or it might just be that the next hall is the last one since they didn't said how many alien invasions are there.
Wait a minute...
Now that two people have died, and the old man is done for. That leaves the remaining participants with three unused phones, yes? The doctor guy probably took one from the corpse already.
This is gonna turn into full mind-game more than it already is.
At first I was trying to figure out whether they can go back to previous hall and use those shelters or not. Then I noticed that there was a mistake in chapter 2; In one panel, the door was close, where it wasn't in another panel. I'll assume they can't but there would be no room for a loop...