Walkthroughs For Xbox360 Games: Bioshock Walkthroughs

Built in 1946 by Andrew Ryan, Rapture was designed to be entirely self-supporting, with all of its electricity, food production, water purification and defense systems powered by undersea volcanic openings. A scientific discovery upset the balance of the society. Two scientists studying squid like creatures discovered a species of sea slug that could secrete stem cells. These could be used to enhance one's body, improving physical or mental capabilities, curing diseases and healing injuries. A young entrepreneur named Frank Fontaine invested early on in the research to gain control over the material dubbed "ADAM". It became so sought after in the society that it became the dominant currency of the city. A "full-scale genetic arms race" broke out between Ryan and Fontaine as Fontaine's monopoly on ADAM threatened the current social structure. Ryan eventually won, but everyone in the city was permanently changed. During the war, it was discovered that ADAM could be used to modify one's body, combining technology and mutations to adapt and survive the conflict, but losing their humanity in the process. During the conflict, all natural sources of ADAM were destroyed, which eventually resulted in a major shift in the "ecology" of the city, as all inhabitants had become biologically dependent on ADAM to survive. On December 31, 1958, attacks with biological weapons lead to the downfall of Rapture's society, and the city fell into a state of disrepair.
The game opens in 1960. The player assumes the role of Jack, a passenger on an aircraft that crashes into the middle of the Atlantic Ocean as he reads a letter from home that ominously begins "Dear Jack, would you kindly...", with the rest of the letter obstructed (it is later revealed the whole content of the letter during Andrew Ryan's speech at his office. It says: "To Jack, with love from Mom & Dad. Would you kindly not open until 63° 2° N, 29° 55° W").

source:- Bioshock wiki

Welcome To Rapture
Part 1