The Batman games released over the last seven or so years have all been packed with secrets and teasers, some of which have heralded what's next for the Dark Knight's future adventures. Arkham Knight players have been searching the new Bat-game for a hidden locale with no luck. Yet.
It's become something of a tradition to sift through the Batman Arkham games for easter eggs and clues about subplots that explain more of each title's eventual successor. The secret room in Arkham Asylum gave a big ol' hint about Arkham City:
And elements of the doomsday attack on Gotham that happens in Arkham Knight came to light in Arkham City's hidden Scarecrow room:
(2013's Arkham Origins had one, too, but the hidden room in that WB Montreal-made game wasn't foreshadowing the latest game made by Rocksteady.)
Since Rocksteady's done this each time out, it stands to reason that there's yet another room tucked away in Arkham Knight, right? But, so far, the search hasn't turned up anything. Here's a snippet from a subReddit thread on the quest to find a secret room:
As the thread mentions, because Rocksteady has said that Arkham Knight is the last game in a trilogy, some people think that there might not be a secret room at all. It should also be noted that Arkham Knight's 100% ending sort of fulfils the purpose of previous games' hidden areas. The heretofore undiscovered teaser space might not exist at all, but it's taken years to find some of the Batman Arkham easter eggs in other games. So this hunt will probably go on for a while