I have one question about the ending.
Why did Comstock/Booker gave off Anna/Elizabeth to those people through the portal? I'm kind of confused and the ending was so overwhelming.:P
[spoiler] Okay, some context first. The Lutece twins invented the time tear mechanic and that's how Comstock saw all his "Prophecies". But by using the machine he couldn't have children anymore due to radiation exposure or something like that but he really wanted a kid. So he knew at some point in time Booker (himself) would have a gambling problem and would easily give up his daughter for a promise to wipe away all his debt. So he went to another universe/time and said he would wipe away the debt if Booker sold his daughter to him. Booker agreed but then regretted it and followed Comstock. When he tried to pull the child back her pinky got severed in the portal, her body being in two timelines/universes at once gave her the ability to tear between universes [/spoiler]
Hope that cleared things up a bit