#plasmid

I could see it being about you playing as someone who lives on an island city, until the citizen's of Rapture invade it. You and a few other people survive the first part of the invasion, but now you need to find a way off the island AND stop this invasion before the residents of Rapture start their next step towards world domination. The bad endings of both Bioshock games always hinted at someone using Rapture's tech and knowledge to rule the world, so a game about that actually taking place would be interesting.

Throughout the game I can see it being revealed that the leader behind the invasion was either some kind of CEO or former government guy who after years of hearing rumors of Rapture and tracking people who just "popped up" over the years, led to them finding the remains of Rapture. Thinking back despite how I always thought it was implied you can't escape, there are a lot of times in the games and other content where people who lived in Rapture were able to escape and go back to the surface, so I wouldn't be surprised if either some news about Rapture got spread or some people started to put the pieces together. That would make for an interesting subplot for the game, while maybe having a nice reference to how there was this old ARG like viral game about a guy looked for kidnapped daughter and collected Bioshock 2 themed data about what was going on.

I can see a Bioshock 3 having a lot of references to the other games, one being that maybe as another twist you play as someone who is related to a previous character like an older version of one of Jack's daughters. I also could see the game having a working Teleportation Plasmid that is more used for dodging attacks and getting around the map faster, working like the Warp Pack from Helldivers 2. I also could see a reference to Infinite where you could see the Lutece twins or Elizabeth.