The Flashpoint skin is one of the best-looking alternate costumes you can get in Batman: Arkham Knight. It references the popular Flashpoint comic series where Thomas Wayne, not Bruce, is Batman in an altered timeline where a war between Aquaman and Wonder Woman threatens to destroy half of the world.
Did You Know
The storyline was closely adapted in the Justice League: The Flashpoint Paradox animated movie.
Unlike Bruce, Thomas has a very different style of delivering justice to the villains of Gotham City. He has no qualms about beating them to death and uses pistols with live ammunition. You will not be able to do that in Batman: Arkham Knight, but the Flashpoint costume does add a new flair to your gameplay.
How to get the Flashpoint Skin in Batman: Arkham Knight
You can only unlock the Flashpoint skin by buying the season pass. This gives you access to all of the post-release content add-ons which include the Batfamily mission episodes, new challenges, and multiple skin packs.
You can also buy the Premium Edition to unlock the Flashpoint skin which includes both the base game and the season pass.
The season pass retails for $20 on Steam as of today but you can take advantage of the upcoming seasonal sales to save a few bucks. Do note, though, that the Flashpoint skin is not sold separately. You have to buy the whole season pass to unlock the Thomas Wayne alternate costume. There is no other way.
The Flashpoint skin is unavailable
This is because the Flashpoint skin is an add-on for the Batman: Arkham Knight season pass. You cannot buy the skin separately. You have to buy the whole season pass, or the premium edition if you do not have the base game.
Something to note for console owners is that buying the season pass does not automatically download all of the new content. You have to open Batman: Arkham Knight from your library and select/download the skin from a list of add-ons.
The Batman: Arkham Knight season pass listing on Steam makes no mention of the Flashpoint skin. This is because the product listing was never updated to add the complete content you get after buying the season pass as shown in the image below.
You do not have to worry though. The Flashpoint outfit is available with the season pass on Steam. It has not been removed for PC.