BioShock 2

Bioshock 2
The development of Bioshock 2 was announced on the 11th of March, 2008. It is set for release in October 2009, under the title Bioshock 2, not Bioshock 2: Sea of Dreams.

There is seldom other information about it, only speculation that it is a prequel to the first Bioshock, set during or before the 1959 New Year's Eve Riots, where the player is a member of Rapture Security. Comments on the below linked page suggest a "Big Sister" & rumors of the player being Jack's son. Which would not make sense were it a prequel.

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