- B-Team Sequel: 2K Marin took on the task of creating a direct sequel to BioShock to free up Irrational to work on BioShock Infinite, which, as it involved an entirely new setting, took much longer.
- Defictionalization: NECA has replicas of the EVE Hypo and Big Daddy dolls, just in case your normal Little Sister wasn't creepy enough. They also have one for the "bunny" and "wielder" Splicer masks.
- Name's the Same: This game isn't the only work to have character named Grace Holloway.
- Throw It In!:
- "Something in the Sea" wasn't going to have an effect on the main game, but fans loved it so much that protagonist Mark Meltzer was given a minor role.
- Apparently, Sheryl Lee of Laura Palmer fame ended up in the recording studio due to a scheduling mishap (likely due to confusion with Sheryl Lee Ralph, the voice of Grace Holloway). She was given a role as a Baby Jane splicer in the Atlantic Express, discussing Jack's whereabouts.
- What Could Have Been: A cut idea for the plot would have involved Soviet soldiers invading Rapture. Part of the AI coding intended for the Russians eventually ended up being used by the splicers instead.
- A removed message from Eleanor revealed that Delta is her biological father (Sophia picked his DNA randomly from a bunch of archived DNA).
- Dionysus Park was originally conceived as being as a perfectly intact area that wasn't leaking and falling apart like the rest of Rapture. The player was originally supposed to get there by way of an underwater section through a completely flooded Fort Frolic. The area would have been home to wild parties hosted by the famous filmmaker Ava-Marie Tate. Stanley Poole, who was so delusional from splicing that he believed he was still the Moral Guardian Intrepid Reporter he once was and was implied to be Grace Holloway's husband, tasked Delta with getting Tate's parties on film. Delta would have taken an ADAM-derived drug called Eden, which would cause hallucinations such as images from his past, large marionettes, and Sander Cohen as a 20-foot tall bunny. However, the footage would have shown that Stanley was spliced up himself and had sold Eleanor to become a Little Sister, causing him to Go Mad from the Revelation and attempt to "erase" Delta.
- The Rumbler is an updated version of a cut Big Daddy from the previous game (which even made it onto some screenshots) code named "Slow-Pro FUM" ("slow-moving, projectile-shooting, f'ed-up-melee"). The Slow-Pro had a single cannon which he had to kneel down in order to use and a huge hook for heavy damaging melee attacks in case the player got close. The Slow-Pro ended up being cut late in development, much to the chagrin of the designers. Eventually it was reworked into the Rumbler, with the hook replaced with the mini turrets (since they believed the Bouncer had the heavy melee department covered).
- Originally there was only going to be a single Big Sister who would be the real Big Bad of the game: one of Jack's rescued Little Sisters who couldn't adjust to life on the surface and would return to Rapture and recreate her childhood by kidnapping children to make into new Little Sisters. In another version, Sofia Lamb would still be the Big Bad, but there would still be a single Big Sister as The Dragon, which would be revealed to be Eleanor (hence why in Audio Diaries, Sofia still refers to Big Sister in the singular). Thus you would fight the Big Sister in a series of Hopeless Boss Fights where you had to survive and damage her enough for her to retreat. Eventually the developers scrapped this since they felt knowing that the Big Sister would always escape would undermine the excitement of the battles as well as feeling that "the Big Sister being YOUR Little Sister" was a weak twist. In a way they partially kept the twist, with ONE of the Big Sisters being the protagonist's Little Sister-only she was Delta's Little Sister, not Jack's.
- Subject Delta's armor used to be based off of old World War II bombers and would have been a lot more top-heavy and bulkier◊.
- Speaking of armor, originaly Delta was going to be a lot more durable, on the level of other Big Daddies. The idea was that individual splicers would be like flies, but become a threat in swarms. In the final product, Delta is just as squishy as Jack, if not more so.
- Many promotional images show Big Sisters with a bayonet attached to their left arm rather than a long syringe, and without a harpoon and wrench strapped to their right arm.
- You could use Pneumo Tubes to buy and sell supplies with non-spliced survivors who had barricaded themselves from the splicers. Ultimately this idea was cut along with the survivors, whose model was re-used as a splicer model in the game's opening.
- Failed "Little Brothers" who were too aggressive to be used for gathering would have appeared in Inner Persephone. A Little Brother therapy room in Inner Persephone was repurposed as a Pediatric Ward for the Little Sisters.
- A concept pitch for a re-imagined Vita-Chamber◊ mentions an "alternative generation of Big Daddys & Big Mommas", suggesting female Big Daddies were considered, as they never appear in the franchise except for the three female multiplayer characters.
Trivia / BioShock 2