Batman: Arkham Knight technically has only one ending which is split into two parts. Depending on how much of the game you have completed, you can either unlock an incomplete (half) ending or the complete (true) ending which is the same as the first one but with a few surprises.
The AR Challenges and the Season of Infamy DLC do not affect the ending you unlock. You can ignore them to save time.
Both endings, though, revolve around Knightfall Protocol. It is code for a contingency plan that Batman put into place if his real identity was ever revealed. Should the villains of Gotham City know that Bruce Wayne is Batman, they will come after all his loved ones, including Alfred and the other Bat family members. Knightfall Protocol was to put an end to that by essentially ending Batman.
Did You Know
After the investigation of Deadshot at Slugg Industries, Batman gave orders to Alfred to install explosives at the foundation of Wayne Manor for Knightfall Protocol. Bruce hoped that it would never be used but kept it as a contingency plan if the lives of his loved ones were threatened.
Knightfall Protocol Incomplete Ending
The first ending is essentially the conclusion of Scarecrow’s storyline in Batman: Arkham Knight. You cannot, however, just rush through the main story to get the ending. You need to complete any seven out of the 14 Most Wanted side missions to unlock the final Knightfall Protocol objective.
Considering how lengthy the Riddler Challenges are, we recommend you save your time by ignoring his missions for the incomplete ending.
Follow your mission marker to the Bat-signal at the top of the GCPD building and activate the Knightfall Protocol. This will trigger the ending cinematic scene in which Batman takes off his cowl for the last time before heading back to Wayne Manor.
There will be dozens of reporters waiting outside the gates to speak with Bruce Wayne who the world now knows to be Batman. However, the entire mansion will go up in flames in a giant explosion as soon as Bruce walks into Wayne Manor, marking the end of both Bruce and Batman. It is never revealed though whether he and Alfred survived.
This cinematic sequence is only a fraction of the complete Knightfall Protocol events in Batman: Arkham Knight. If you want to know about the fate of the Dark Knight, you need to fulfill more requirements to unlock the complete ending.
Following the half-ending, you will be taken back to Gotham City to complete the rest of your missions. You can then re-activate Knightfall Protocol for the full ending.
Knightfall Protocol Complete Ending
Unlocking the true ending of Batman: Arkham Knight requires you to complete all 14 Most Wanted missions which include clearing all the road checkpoints, rooftop watchtowers, weapon caches, and crime victim locations.
Most importantly, you need to also apprehend the Riddler which will take a lot of work. You need to find all of his Riddler Trophies, solve all of his Riddles, and save all of the Bomb Rioters. Initiating the Knightfall Protocol without completing all of Riddler’s Revenge Challenges will not get you the complete ending.
You need to also find all of the Batgirl: A Matter of Family DLC Collectibles for the complete ending.
Once you have completed all of the side missions, you can head over to the GCPD rooftop to initiate Knightfall Protocol again. What follows will be the same cinematic but with a few additional scenes.
Firstly, the Bat-signal will go out when Batman leaves the rooftop. He will also leave a message for Commissioner Gordon to let the GCPD go after the rioters.
The Wayne Manor explosion scene remains the same, but after that will be a new monologue from Gordon. He will be voted in as the new Mayor of Gotham, and Tim Drake (Robin) will be set to wed Barabara Gordon (the Oracle).
Wondering who will take Batman’s place as the new protector of Gotham? The true ending of Batman: Arkham Knight finishes with a little secret. A scene plays in an alleyway on Miagani Island where a couple of thugs are robbing a family of three. It is similar to what happened to Bruce as a child.
The robbers then notice that there is someone like Batman standing on a nearby roof. Taunting him that Batman is dead, the figure starts to fly and then bursts into a fiery flame before dashing towards them.