Throughout Bioshock, right from the first 10 minutes of the game, you are asked by a man referring to himself as Atlas to do numerous things to help him and his family. This starts when you first enter Rapture, where he says 'Would you kindly pick up that short range radio'. From there, he says you're going to have to trust him, and tells you to get out of the sub and move to higher ground. Once there, he activates security systems to save you from a splicer, then asks you 'Would you kindly find a crowbar or somethin'. He tells you that he and his family are trying to escape Rapture, and they need you help. He asks 'Would you kindly lower your weapon' when you first encounter a Big Daddy and Little Sister, saving your life most likely. 'Would you kindly go to the medical centre' is one of his next requests, to help you reach his family in Neptune's bounty. When in Neptune's Bounty, you are directed to a sub he says contains his family. He asks 'Would you kindly open the release valve', or something along those lines to let them escape. Andrew Ryan, the owner of Rapture (Who you have seen before, and who has always been hostile to you) then tells you not to interfere or something, and blows up the sub. Atlas asks 'Would you kindly go to [X]' (Forgotten where), and you being a journey for your revenge against Andrew Ryan. Those who have played the game will have already seen the pattern, those that haven't may not have. Your quest for revenge against Andrew Ryan comes to a climax when you finally go to confront him, and Atlas says 'Would you kindly head to Ryan's office, and kill the son of a *****'. In the room before Ryan's office, this is what you see:
http://images.wikia.com/bioshock/images/0/0f/Would_You_Kindly.png
Well S***.
The tape recording nearby tells the story of how a baby was genetically grown in 2 years as the illegitimate son of Andrew Ryan, which ties into other previous tape recordings from Andrew Ryan's love, and his mistress who he impregnated, and who lost the baby somehow (Forgotten how).
You move into the next room, and confront Andrew Ryan. This is what happens (Up until 3:50):
http://www.youtube.com/watch?v=bncxTilQKAs
As soon as you walk into the room with Andrew Ryan in it, and until 3:50, you have absolutely no control over what you do. Whereas throughout the entire game you have felt as if it was your choice to do things, your choice to hunt down Ryan, when you finally confront him, all illusion of choice is torn away and you can only watch as you 'Obey' and kill him. This is very powerful due to how the player perceives themselves as the character, and how powerful taking control away from a player in a game in which they are ALWAYS in control is. Throughout the entire game after the intro sequence, you can always at least look around, if not walk around and pull levers and such. It is that point alone (Pretty much) where you are unable to do anything, and you must just watch as you kill Andrew Ryan, revealed to be your father.