I beat the game last week &, while it was immediately obvious how little sense it makes, the more I think about it the less it makes sense. The problem I have is not with the end game revelation (which I saw coming a mile away. Seriously... the game does everything but straight up tell you that Booker & Comstock are the same person via the voxophones), it is with the time traveling aspect of the ending. This is a very hard topic to discuss as it cannot easily be explained, but the fact is that LOGICALLY the game could have never taken place if Booker was killed before the events of the game.... which by going back in time, he was. If Booker were to have been killed back then, then he would have ALWAYS been dead & therefore the Booker that you were playing as through the game would not exist. Not only that, but if you go by the game's own (somewhat flawed) logic of an infinite number of possible outcomes to every decision, then the ending still comes completely unraveled.... they only killed ONE version of Booker in ONE realm. That still leaves the possibility of Comstock (or perhaps an even worse version of Booker) coming into existence in other realms. I mean, what is stopping a different realm's Booker from refusing to be drowned & killing the Elizabeths that were drowning him? They accomplished nothing by killing the obviously GOOD version of Booker that you played as....

Spoony offers what he thought about the ending really well:

http://spoonyexperiment.com/2013/04/14/bioshock-infinite-review/

They went to the start of the fork that creates Comstock. Even going by the idea that an infinite number of dimensions exists in which every single choice can be played out, all of those choices will still have one main fork. After a 100 or so iterations, Booker reached the path that the player plays through allowing Elizabeth to finally find the original fork that created Comstock.

Now the idea of the ending is that they finally got a Booker to the fork where Comstock is created and finally got him to understand that in order to prevent the entire Comstock fork Booker needs to die at that point. Thus the Comstock that was created as a result of *that* baptism will no longer exist.

Yes, the game doesn't explore the possibility of another Comstock like fork being created at any other point (and going by the infinite dimensions theory, then yes, other Comstock like personalities were created out of other Bookers at other points. But none of those forks involve Elizabeth connected to the Comstock fork explored in the game.

So you can think of it as them killing of one Booker which destroys one possible fork -- the fork that created the Elizabeth we see through the current game.

You could then try to theorise that if Comstock was removed from the infinite possible choices, then Elizabeth was could never have been taken by Comstock -- hence why we then see a Booker going back to that room to check on baby Elizabeth.

As for the whole the game could not have existed if they managed to kill of the Comstock path... that's certainly one way to look at it. But then we wouldn't have had a game =P

I always thought the Booker we see going to check on Elizabeth was the one that wouldn't go through with giving her away, regardless of whether Comstock existed on that universe or not.

That's another perfectly valid possibility. But the tone in his voice, could suggest otherwise.

I don't remember, did he have a nosebleed then?

He did seem worried about her. I took that to mean that he remembered everything that happened in the game, like those enemies you killed in one universe and remembered dying in another. I felt they were throwing a bone to the fans implying a possible happy ending.

I don't recall being shown that he had one. But that's part of the point I guess. It's not explicitly stated so you can pretty much decide for yourself what that final scene means.

It makes perfect sense. It's not time travel, it's universe hopping.

Elizabeth attains her full power because the Luteces laid out a perfect path for Booker. Elizabeth then eliminates Booker's choice after Wounded Knee - there is no more choice to participate in the baptism, and therefore Comstock is never made, and therefore Columbia is never made, and therefore Anna is never taken.

It happened and then it didn't.

so I've finished the game yesterday, and it felt so bad!

it all started with the scene from the future (snowy) where you are repeatedly told you suck, you've abandoned Elizabeth and are basically a dick (even though you do YOUR BEST to save her, fighting your way through, never giving up on her)

after that you come back to present, rescue Elizabeth, kill the person responsible for all of this, but instead of some closure or forgiveness, you realize YOU REALLY ARE A DICK, it's all your fault and you deserve to die :(

I still don't understand why did Elizabeth kill you - you obviously were not the version that became Comstock, so she could just jump to the tear where this "original" Comstock really existed, and kill him (even if that meant killing you in the process as Columbia never existed), but not you in person...

I don't know, it sucked for me...