What does this option at the end of NieR: Automata actually do?

After beating

the credits mini-game

in NieR: Automata's last main ending, you get two options. One of these is

to simply display a message made out of per-selected phrases to display to other players going through the same mini-game,

simple enough.

But after that question, you're given a heftier question. Your pod asks if

you would like to "save" another, random, player. In order to do this though, you must have all of your save data erased. As I'm not yet done getting achievements or side endings,

I said no, leaving me curious as to what he meant. What exactly would have happened

to this randomly selected player

if I had I hit yes?

Would I get any indication of anything that happened as well, or would the pod have just said 'affirmative', erased my data, and send me back to the title screen?

Solution 1:

Ah, the big choice.

Since the ending sequence is nigh impossible without accepting help (this is clearly intentional, as the entire point is that you can't take on enormous tasks alone), you accepted it, right? Every person that assisted you was actually someone who chose to erase all of their save data for this purpose. Had you chose to delete your save, someone out there who needed help on the ending sequence would have gotten assistance from you.

I originally declined in order to 100% the game, but as soon as I had done so, I went back and redid this sequence so that I, too,

could erase all save data in order to assist someone else.

If you choose yes, you will actually be prompted for confirmation about 7 or 8 times before it actually happens.

During the sequence directly following, it will show all of your data being deleted, one item at a time (though many are skipped over so this doesn't take an eternity). The very last part shows all of your save slots being erased. This means you cannot simply copy your save data to a second save data slot. All three are erased entirely. The only record of you having played the game and made this choice is that you will get an alternate background for the title screen. It looks like this:

Solution 2:

The usual claim is (quoting the earlier answer) that

Every person that assisted you was actually someone who chose to erase all of their save data for this purpose.

The idea seems to be that there is, in effect, a counter stored on a Square Enix/Platinum server that increments every time someone

sacrifices their save files to help someone

and decrements every time someone

accepts the help

and when it reaches zero the second action becomes impossible.

That can't be true because of the huge difficulty gap between the incrementing and decrementing actions. (Keep in mind that the counter would be increased by a player only if they performed the incrementing action without previously performing the decrementing action.) In practice the counter would almost always be zero, but public evidence shows that it's never or almost never zero. (I'm not aware of anyone ever being unable to perform the decrementing action, but if that does happen, it's at least uncommon.)

The decrementing action displays the username of someone who allegedly performed the incrementing action. I see no reason to believe that those usernames are made up. Most likely, there's a pool of names on a server, the decrementing action randomly selects a name from the pool without removing it, and the incrementing action adds your name to the pool and removes someone else's (probably whoever's been there the longest) to prevent the size from growing without bound. That would mean that the incrementing action has no effect on the ability of others to perform the decrementing action. The only effect is that they'll see your name instead of someone else's. I think the most selfless action is to give that other person a little more time to shine.

The incrementing action also has a local effect on your machine – see the last spoiler box of the earlier answer if you want to know that effect.