It seems that the final installment of Rocksteady’s Batman Arkham video game series will be a bit more “mature” than the first two. The studio says that the ESRB has given Batman: Arkham Knight an “M for Mature” rating.

Rocksteady’s previous Batman games, Batman: Arkham Asylum and Batman: Arkham City, both received “T for Teen” ratings (as did the prequel Batman: Arkham Origins, developed by WB Games Montreal). Sefton Hill, Rocksteady’s founder and director on Batman: Arkham Knight, says the rating to him and the studio by surprise.

"From our point of view, we never wrote it or made it with a rating in mind,” Hill tells IGN. “We never did that in the previous two games... We just felt that this is the story that we really wanted to tell."

Hill goes on to say that he and the studio are aware that the M rating might keep the game out of the hands of some younger fans of the franchise, which could hurt its marketability, but says it’s important not to compromise the game’s story.

"I'm not blind to the fact that [the M rating] does mean some fans will miss out... I don't want to be oblivious to that fact,” Hill says. “It would have been wrong to water down the game and deliver a story we didn't believe in to keep the game 'mass market' or enable it for more people. We feel that's the wrong way to go about it. We said we love the story and we don't want to jeopardize that."

Batman: Arkham Knight will be released June 2.