It appears to be a false alarm. Mark Hamill retweeted the same tweet but without a “s” on Arkham Knight.
Mark Hamill may have accidentally revealed the name of the next game in the Arkham series, and it will apparently be titled “Arkham Knights”.
Yesterday an interview with Mark Hamill came out where he talked about keeping a secret or else he wouldn’t get paid. Everyone (including myself) assumed he was talking about The Force Awakens, but it turns out he’s staying quiet about his role as the Joker in the next Arkham game.
In a Tweet that has since been deleted, Hamill clarified that he doesn’t have a payout waiting for him if he keeps secret about Episode VII…it’s “Arkham Knights” that he can’t talk about:
2015-11-20 01:47 UTC
The bonus I meant was for returning as Joker in Arkham Knights. I’m keeping my big mouth shut about Ep VII for free! https://twitter.com/SteeleWars/status/667472924283006976
Batman: Arkham Knight was Rocksteady’s final game in their Batman series. That means that whoever is making “Arkham Knights” isn’t them, but likely WB Montreal who did Arkham Origins. Warner was also rumored to be doing a Suicide Squad game to coincide with the movie’s release in August. It’s unknown if that game is still coming.
There’s also a possibility that Arkham Knights isn’t even a game, but another animated movie. However the ending to Arkham Knight does leave the door open for a “We Are Robin” style storyline where multiple people take up the mantle of Batman. It’s also entirely possible that Hamill was just joking, but the Tweet was deleted for a reason.
Perhaps we’ll learn more at E3 this summer.