Although even developer Rocksteady Studios was surprised to learn Batman: Arkham Knight had been rated "Mature," we now have a good idea of why it's the first game in the franchise not to receive a "T for Teen."
Fan sites Batman News and Arkhamverse note the the Entertainment Software Rating Board (ESRB) has published its rating summary, which lays out the factors leading to the decision. While many of the elements are present in earlier games, scenes of torture would seem to be what pushed Arkham Knight into "M" territory. Note: The ratings summary may contain game spoilers.
Content Descriptors: Blood, Language, Suggestive Themes, Violence
Rating Summary: This is an action-adventure game in which players primarily assume the role of Batman as he battles several villains spreading chaos across Gotham City. Players traverse a variety of locations around Gotham while battling thugs, examining crime scenes, and occasionally rescuing hostages. Players engage in melee-style combat using punches, kicks, and gadgets (e.g., batarangs, explosives). Enemies cry out in pain when struck, and some takedowns are highlighted by brief slow-motion effects and loud impact sounds. Some sequences allow players to use tank-like vehicles with machine gun turrets and rockets to shoot enemies; a vehicle's wheels are also used to torture an enemy in one sequence. Cutscenes depict characters getting shot (on and off camera) while restrained or unarmed. Large bloodstains/pools of blood appear in crime scenes and in the aftermath of violent acts; one room depicts a person torturing a character on a bloody operating table. During the course of the game, players can shoot unarmed characters and a hostage. Neon signs in a red-light district read “live nude girls” and “XXX.” The words “b*tch,” “gobsh*te,” and “a*s” appear in the dialogue.
Rocksteady founder Sefton Hall said two weeks ago that no changes will be made in an effort to secure the "T" rating, explaining it would be “wrong to water down the game” to appeal to the mass market.
Scheduled for release June 2 from Warner Bros. Interactive Entertainment, Batman: Arkham Knight follows the Caped Crusader at the peak of his abilities, as Scarecrow returns to Gotham City to unite his foes to finally kill the Dark Knight.