Very little has been revealed about BioShock 4, but previous iterations might have some clues as to where the next entry could lead. 2013's BioShock Infinite took players to the flying city of Columbia, leaving behind the underwater city of Rapture seen in BioShock 1 and 2. However, a major confrontation at the end of Infinite ends with a brief trip to Rapture, revealing that every BioShock game so far takes place in parallel universes.
Though this complication was originally assumed to be specific to Infinite, there are some clues in the original BioShock that suggest the games have existed in a multiverse since the very beginning. If this is the case, then developer Cloud Chamber Studio might need to find ways to connect BioShock 4 to the first game from the series.
BioShock: Songbird's Swan Song
Careful Planning or Clever Trick?
Of course, that level of foresight would imply that Songbird had been fully designed in 2007, six years before Infinite's release and six months before development on the title even began. Assuming the sound is actually meant to be Songbird, it's far more likely that the creature's telltale screech was created to sound somewhat similar to the ambient noise in BioShock 1. The original game was filled with strange sights and loose story threads, so developer Irrational Games would have been spoiled for choice when looking for connections to BioShock Infinite.
It's worth noting that the specific sounds Songbird makes during its death scene in Infinite don't quite match up to the faint sounds heard in BioShock. This likely means the scene was changed in Infinite, or could be proof that the sounds heard in BioShock aren't Songbird at all. It could also mean that there are multiple universes in which Songbird suddenly appears in the ocean, and that Booker and Elizabeth don't actually visit the same universe seen in BioShock 1. While it would be a disappointing to see such a tantalizing fan theory debunked, it would mean that Rapture also exists in infinite universes — including one where the city never collapses.
"There's always a city."
If BioShock 1 and BioShock Infinite are as intricately connected as it seems — and Infinite's DLC campaign Burial at Sea leaves little doubt that they are — then Cloud Chamber Studio has a lot of major decisions to make while developing BioShock 4. Most critically, it has to decide whether players will revisit Columbia and Rapture or stay in the same city throughout. Infinite's Tear system showed that there are countless versions of any given city, so players might have the opportunity to explore some of those alternate realities. There might also be more than one new city, giving players the opportunity to explore a variety of new environments.
The developer will also need to decide how seriously to take Elizabeth's statement that "There's always a lighthouse. There's always a man. There's always a city." That line suggests that all future BioShock games must contain those elements, but it also assumes that Elizabeth has seen all potential realities. It's possible that her statement was only specific to the universes that she's a part of, and that there are separate multiverses which defy that cycle. If that's the case, then BioShock 4 wouldn't need to intersect with the stories of Columbia and Rapture at all. Such an omission would be risky, but if BioShock fans have learned one thing, it's not to trust their expectations.
BioShock 4 is currently in development.