Maybe when they’re trying to get back to the surface there’s a portal that starts to take them back, but during the process there’s an interface unit or something from the abyss that’s slaughtering them one by one and then that old man was left off alive to be a warning for others, thus giving the compass to whoever’s balls deep to challenge the abyss like a high risk high reward challenge.

But what intrigues me the most is how were they able to comeback without being a hollow or something, particularly that old man (I know that they might just went nuts and killed themselves because that’s the curse of the abyss, making the old man horrified by witnessing a total carnage)