Parallel Worlds (spolier for Bioshock infinity)

parallel world is a concept that believes there are multiple universe lined up in parallel. Alternative history is the one of sub genre of parallel world which basically starting from one basic question, what if? For example game Wolfenstein is about the world what if Hitler won the world war 2. Bioshock Infinity is all based on this conceptual idea of what if 19 century pre-war american were able to create hyper technology that could able to create flying city. In the game they explain this idea by using symbolistic building, a light house.

At the beginning of the game main charcter (Buker) enters the lighthouse to enter a flying city. It is working as a door way to a city but when it is near the end game explain further this idea of door in different way. Near the end he enters this light house again but when he opens the door instead of interior mutliple lighthouse shows up. Then unplayble character Elizabeth start to explain multiple dimension which what each light house represent, another universe. It is started from very simple choices which what Buker had to do after a war against native Americans. He wished to become a another person because he was haunted by the war. At this point two big universe were created which universe that Buker did not accept Baptism and the other one which he accepts it.

 
Whole story of Bioshock is based on this choice because he founds out that Comstock who is the main villain in the game is actually himself from different universe. When comstock finished building his own country he founds out that he were not able to create baby. He decide to open a portal to another parallel universe that he actually have a baby then took the baby from there which is the universe where Buker exist.

In the end they realise that they could not stop comstock because there are infinite amount of universe. So they try to eliminate choices from the beginning so it could not exist in the first place. In a result Elizabeth kill Buker before his bapism. The ending was imilar to a movie Butterfly effect.