Not just one awesome leak, but two!
At this stage in the rollout of Arkham games from both Rocksteady and Warner Bros. Montreal, you're either in two camps: 1. The basic 'Batman combat' is just as enjoyable as it ever was, and you can enjoy the games as throwaway Joker-thwarting romps without worrying about how similar each one feels. Or 2. Arkham Knight was the last time you were actively excited to jump back into that mould - a notion bolstered by Rocksteady returning, who have now departed for this next game.
Because like it or not, the Arkham games make a TON of cash, and with Rocksteady bowing out of the franchise mostly with grace (save for that weirdly open-ended 'Fear Toxin secret ending', anyway), it's over to WB Montreal to pick up the pieces.
To that end, we already knew another Arkham game would come at some point, and thanks to a massive leak from a disgruntled Warner Bros. employee spilling their guts all over Reddit, we know absolutely everything about the next game in the series, Arkham Insurgency.