How big does a classic labyrinth need to be to reliably kill those trapped within by means of exhaustion and dehydration?
The labyrinth would be fair - meaning there is an exit that one could theoretically get to. The idea is that the maze is so massive and confusing that the victims would die before they could walk out.
On the other hand, taking into account that cracks in the underground walls could seep life-saving moisture, perhaps it’s better that it also be built to kill by starvation. I think dehydration is only three to five days, but starvation is closer to a month or more. This way only those who resort to licking moldy cracks in the walls and cannibalize each other could actually win.
Multiple levels seem like a given. Along with stairways that skip entire floors and go nowhere. Points awarded for keeping the square footage under miles.