BioShock Infinite: Burial at Sea is a two-part single-player expansion to BioShock Infinite. Burial at Sea primarily takes place in the underwater metropolis Rapture before the events of the first BioShock game. Development of Infinite's downloadable content commenced immediately after finishing the main game. Irrational Games was drawn to returning to the setting of Rapture and using Infinite's gameplay systems to create a version of the city before its ruin in BioShock. Reception to Burial at Sea's two episodes was mixed. While the return to Rapture was generally praised, the first episode drew criticism for its short length and a lack of differentiated gameplay. Reviews for the second episode were more positive, with multiple critics calling Burial at Sea a fitting swan song for Irrational's work on BioShock, as the studio reorganized.