Once again, you'll be able to play as the villain by pre-ordering Batman: Arkham Knight. While Origins let you play Deathstroke, the upcoming next-gen game will let you play as Joker's second-in-command, Harley Quinn.
According to the official website, pre-orders will receive the Harley Quinn add-on. "Become Harley Quinn for the first time ever in an Arkham game and utilize her unique weapons, gadgets, and abilities first-hand," the promo reads. And as always, "the add-on includes four exclusive challenge maps." Just in case you were afraid challenge maps wouldn't return.
Finally, according to GameStop's pre-order page, it appears the game is scheduled for an October 14th release. Given its AAA status, it's unsurprising that WB would want to aim for the start of the busy holiday shopping period.