Rocksteady's Arkham games have turned into a kind of Batman franchise hall of fame. You haven't really made it until whatever villain or costume or gadget you created gets tucked away in some corner of the games' massive worlds. And next month, fans of Tim Burton's take on the character will be able to rest easy. Anyone who bought the $40 "season pass" to Batman: Arkham Knight (yes, on top of the $60 game) will soon be able to swap their Batman for one from the 1989 film, and they can turn their Batmobile into Michael Keaton's slick retro ride. Except that Michael Keaton couldn't also use his car as a tank.
Arkham Knight already includes a number of extra skins and Batmobiles, including a '60s Adam West costume. While some of them are available for everyone, publisher Warner Bros. parceled others out as "exclusives" across platforms, retailers, and game editions. You basically need a chart to keep track of them. But 1989 Batman is just a way to reward people who paid for six months of extra maps, designs, and missions after the game's launch. Today also marks the release of Arkham Knight's first real extra storyline, starring Batgirl. Sadly, this is all moot for PC owners; the game's many technical problems aren't supposed to be fixed until fall, and the lost souls who already bought it will have to wait on Batgirl.
It's also not the only new costume coming in August. There are three more Batmen (a '70s version, an "iconic gray and black" one, and one from prequel Arkham Origins), as well as Robin from the "One Year Later" comics arc; the slightly more emo version of Nightwing from older game Arkham City; and a purple, non-Michelle Pfeiffer '90s Catwoman. They're all featured above, but frankly, you might want to wait for the chart.
Polygon Video: Arkham Knight gameplay overview