Free Flow Fifty Achievement Ti...
	Skins...
	Various Steam Achievements...

An easy way to score the x50 combo needed to earn this Achievement is to reach Round 4 of the "Intensive Training" combat challenge. At this point, abuse the trick of attacking enemies, then jumping over them to avoid their hits/counterattacks. Simply continue this until you reach a x50 combo, without worrying about using combo attacks or finishers (indeed, these attacks will finish enemies off quicker, potentially throwing off your timing). It gets even easier if you have unlock the Shock Gloves, which provide a x2 multiplier on each successful hit when activated.

Skin	How to unlock
Adam West & Futuristic Batman Costumes	Get the 'Knightfall Pack' as a PS3-exclusive pre-order bonus.
Batman 1 Million Costume	Register with WBID when starting a new game.
Batman Blackest Night Costume	Earn Prestige in Multiplayer Mode.
Batman Costume	Available from the start of the game, as soon as you begin the Story Mode.
Batman Dark Knight Costume	Finish all Dark Knight Challenges.
Batman Injustice Costume	Earn all Medals in the game's Challenge Mode.
Batman New 52 Graphic Costume	Capture every Most Wanted target in the game's Story Mode.
Batman Noel Costume	Complete the campaign.
Brightest Day Batman, Gotham by Gaslight Batman Costumes	Get the 'Batman Arkham Origins - Season Pass' on your system's online store.
Earth-2 Bruce Wayne, The Long Halloween, Earth-2 New, Batman Thrillkiller, Knight of the Round Table, 1989-2006 Classic Tim Drake Robin Costumes	Get the 'Infinite Earths Pack' on your system's online store.
First Appearance 1939, Red Son, Noel, New 52, Blackest Night 2006-2008 Tim Drake Robin Costumes	Get the 'New Millenium Pack' on your system's online store.
Initiation Bruce Wayne skin	Get the "Initiation" DLC on your system's online store.
Judas Contract Deathstroke, Injustice Deathstroke, Arkham Origins Deathstroke Costumes	Get is as a pre-order bonus in selected stores. Will soon also be available to buy as the 'Deathstroke Challenge Pack".
Long Halloween, Batman ThrillKiller, Batman Earth 2, Batman: Dark Knight of the Round Table Costumes	Get the 'Batman Legends Pack' as a pre-order bonus in selected stores.

Note: Some of the skins require to buy an in-game DLC.

Achievement	How to unlock
Air Marathon	Glide 26 miles total.
Anyone see that?	Complete a predator encounter without ever being spotted.
Around the World	Use the Batwing to travel to all Fast Travel points.
Arsenal, Awesome	Fully upgrade a weapon in multiplayer.
City of Assassins	Identify Black Mask's assassins.
Clean Streets	Complete all Most Wanted missions.
Clutch	Kill a Hero to bring back your entire gang when at 0 reinforcements on a full multiplayer server.
Counter-intelligence	Decipher one Extortion File.
Crime Fighter	Stop 20 Crime in Progress.
Crime Scene Investigator	Complete all Casefiles.
Enigma Unravelled	Collect all Enigma items.
Everyone wears masks	Find the Black Mask.
Fallen Knight	Reach max level with the Bane faction in multiplayer.
First Riddler Trophy	Collect every collectible.
Flawless Display	Successfully battle Shiva without taking any damage.
Free Flow Fifty	Reach x50 Combo.
Give Them Something to Believe	Complete New Game Plus.
Gotham All-Star	Reach max overall level in multiplayer.
Gotham Protector	Master the Gotham Protector Dark Knight track.
I Am The Night	Finish I Am The Night Mode.
I Like Those Odds	As a Hero, defeat 4 Elites within 40 seconds without using melee in multiplayer.
I've Got This	Acquire all upgrades.
Killing Joke	Reach max level with the Joker faction in multiplayer.
Know Thy Enemy	Defeat each of the enemy players at least once in a multiplayer match.
Legend	Earn a level of prestige in multiplayer.
Legend of the Dark Knight	Complete all Dark Knight challenges.
Medalist	Obtain all medals on the original Ranked Maps in Challenge mode (as Batman).
Nobody that matters	Who is the Joker?
Not An Ordinary Criminal	As an Elite, earn 4000 XP in a single multiplayer match.
Olympian	Obtain all medals on the original Campaign maps in Challenge mode (as Batman).
One down, several to go	Complete a Most Wanted entry.
One eye open	Defeat Deathstroke.
One of Each	Use every Freeflow Focus gadget in one combo.
One Rule	Save a life.
Perfectionist	Obtain all the medals on Custom maps in Challenge mode.
Perhaps sooner, Perhaps later	Defeat the Joker.
Personal Trainer	Obtain all the medals on Combat Training maps.
Point Counter-Point	Complete Deathstroke without failing a single counter.
Point to Point	Glide across Bridge without touching ground.
Predator Paragon	Take down 6 different Elites in a match, using 6 different methods as Batman or Robin in multiplayer.
Shadow Vigilante	Master the Shadow Vigilante Dark Knight track.
Shut Down	Shut down an entire Tower Network.
Silent Knight	Complete a predator encounter using only silent takedowns.
Tales of Gotham	Win a round of each map with each faction in multiplayer.
Thanks, old friend	Hear everything Alfred has to say.
The Innocent and the Predatory	Capture all of Black Mask's Assassins.
Voice of the People	Scan 20 Anarky Tags.
What hit me?	Take down 100 enemies who didn't know you were there.
World's Greatest Detective	Master the World's Greatest Detective Dark Knight track.
Worst Nightmare	Master the Worst Nightmare Dark Knight track.