The name of the "Final" map has multiple references and meanings. As we know, "Nacht der Untoten" translates to "Night of the Undead", where "Tag der Toten" tranlates to "Day of the Dead" thus being an inversion, possibly implying the end is the beginning which could mean many things: either there is no solution to breaking the cycle or just meaning we're getting a story "reset" theoretically. It could also be a well thought out and convoluted reference to the idea of "Revelations" being the end and beginning. Either way this also means that the title is also technically a reference to "Alpha Omega" or "Beginning of the End" making this the end, side note "Revelations" is technically the alpha and omega, or beginning and end.

"Day of the Dead" is also a reference to a George Romero movie of that name.

Both "Ascend from Darkness" and "Salvation Lies Above" are callbacks to the "Origins" achievement, which was also a reference to "Nacht". They may also be references to the COTD Easter egg step, which required you to make npcs "ascend" the lighthouse.

If you can think of anymore references, feel free to comment them. These are just the ones I can think of at one in the morning.