[新闻] 生化奇兵4：双城之战 ？

He also posted what seems to be a slide from a pitching presentation of the game that describes the concept of an in-game city, actually two cities, with radically different ideology, where one of them located underground right below the other, both sharing a "flipside" border zone with an unleashed "vertical war".
https://www.reddit.com/r/GamingLeaksAndRumours/comments/r4k7nj/bioshock_4_logo_and_pitching_presentation_might/