Note: Perform this while offline (not logged into Xbox Live or PlayStation Network as your system date is automatically set via the internet). Set the date of your console to a holiday date (for example, January 1, February 14, etc.) and load a saved game file where the story progress is past rescuing Catwoman. Enter the courthouse and speak to Calendar Man in the basement. He will tell you a story about the current month's holiday and tell you to return for the next month. Save the game by leaving the building. Exit to the system settings, then manually change the date to the following holiday. Repeat the process until you have cycled through the entire calendar year. The calendar on the wall next to his cell will highlight the holiday dates for the current year and scribble out which months you have already spoken to Calendar Man about.
Complete the game under the Normal or Hard difficulty setting. This mode allows you to keep your previously obtained gadgets and experience points. Also, there will not be any counter icons on thugs, thugs will be tougher from the start, thugs will have different configurations, and Bosses will be stronger.
Take out your cryptographic sequencer and hold LT and RT. Rotate the left analog clockwise while simultaneously rotating the right analog counterclockwise. Do this until Batmans head becomes big. All enemies will also have a big head.
To make Batman (or any other playable character) perform a "taunt" similar to when starting a challenge map or round, rotate the right analog stick clockwise two or three times. Execute a taunt before performing a glide kick to have the camera change into the enemy's perspective during the glide kick action (only works for Batman or Robin).
Use Batman's Cryptographic Sequencer and track down the XY coordinates 700, 490. You'll intercept a radio frequency that reads these numbers: 9-23-9-12-12-18-5-20-21-18-14-2-1-20-13-1-14 (there will be a buzz sound and repeat these numbers) When matched to the corresponding letters of the alphabet they spell out I WILL RETURN BATMAN.
Locate the coordinates X500.00, Y900.00 on the Cryptographic Sequencer to intercept a radio frequency that contains the following repeating numbers: 5, 15, 9, 7, 21, 18, 18, 14, 3, 5, 24, 15, 12, 7, 22, 3, 10, 5, 15, 9, 22, 3, 8, 25, 26, 15, 16, 25, 10, 15, 17, 25. When decoded, the message reads "YOU WILL PAY FOR WHAT YOU HAVE DONE TO ME".
Using the cryptographic Sequencer, set the coordinates to 200, 500. A voice will speak these numbers: 3-20-26-18-26-16-24-1-11-4-24-9-3-8-5-2-12-18-6-16-7-11-3-10-17-5-13-4-21-8. To decode requires a good amount of work. First, set each number to a letter in the alphabet but in reverse so that Z=1, Y=2, X=3 and so on. From there you use a special cipher known as a Vigenere Cipher that requires a keyword to translate. By using the keyword "scarecrow", the message translates to "FEAR WILL TEAR GOTHAM CITY TO SHREDS". Since the keyword is scarecrow, it is likely that Scarecrow is behind this message and possibly more.
Search the following locations to find the corresponding trophies:
Park Row 1. East of ACE Chemicals is a gargoyle sprayed with Riddler question marks. Climb onto here and drop down to the concealed area below for the trophy. 2. East of Trophy 1 on the roof near a wall with five Riddler question marks on the wall. Use the Batarang to destroy the right-hand Riddler mark by waiting until the light is on. 3. On the building north of ACE Chemicals, behind a ventilation system. Use the remote controlled Batarang to destroy the Riddler mark. 4. On the roof of the building with Park Row written over it on the map. The timed panel is a few steps to the west. 5. On top of the most northwestern building near Solomon Wayne Courthouse. Use detective vision to locate all four Riddler marks. You have 4 seconds to destroy all four marks, so use the explosive gel on the 3 hidden marks, then use the Batarang on the final Riddler mark closest to the trophy’s locked cage. 6. There are three pressure pads in the area. Starting from the northern rooftop overlooking the Riddler trophy, glide on to the southern wall and pressure pad. Quickly after pressing the pad, glide over to the wall on the opposite side then finally onto the pad on the ground closest to the Riddler trophy. 7. A pressure pad on the highest rooftop east of Solomon Wayne Courthouse opens a gate below. Activate it then glide down into the area, then use explosive gel to destroy the wooden panel beneath. 8. Slightly southeast of Trophy 7. On top of the roof with a nearby Riddler mark on a chimney. Use the Batarang to activate it. 9. On the northern roof edge of the large building east of Solomon Wayne Courthouse. Use explosive gel to destroy all three Riddler marks at once. 10. In a passageway at the most northern part of Park Row. Behind a chain fence with a destructible wall on the right. A TYGER camera guards the area. 11. At the end of the destroyed overpass is a selection of shanties. Search beneath the very end of the overpass for a structure with a destructible wall. Use explosive gel on this and search inside for the Riddler trophy. 12. East of the building between the north side of the restricted area and the Church/Medical Centre, opposite a building with a "The Black Canary" sign. Use detective vision to locate the necessary Riddler mark, then use the remote controlled Batarang to activate it from near the Riddler trophy. 13. On the roofs of the buildings west of ACE Chemicals and north of The Bowery is a set of cages with electromagnets. Once you have the REC, use the electromagnets to push the Riddler trophy out of the cage, starting with the bottom electromagnet. 14. Near west side edge of Arkham City, on the roof behind a set of bars. This TYGER panel will require the necessary upgrade before you will be able to hack these controls. 15. In a short passageway along the west wall of Arkham City. Guarded by a TYGER Camera. 16. West of ACE Chemicals, on the roof of the building that runs through the Arkham City wall. Activate the panel by gliding from the top of the nearby gargoyles on the Bank Of Gotham, then use dive bomb to land on the panel. Destroy the Riddler mark with the Batarang. 17. At ground level below ACE Chemicals. Access the cage by freezing the hot air with the Freeze Grenades. 18. Beneath an abandoned car west of ACE Chemicals. Bat-slide underneath it to collect it as you go. 19. Behind a set of iron bars west of ACE Chemicals and next to a short barrier with a "Do not enter" sign on it. Glide from the roof of the building to the north to smash through the destructible wall. 20. On top of the church's roof, locked by a nearby TYGER panel. 21. On top of the church is a short passageway with an electrified fence and a destructible wall. Use the REC on the fusebox and explosive gel on the wall to collect the Riddler trophy. 22. In the alleyway behind the church is a cage with a set of pressure pads. You won’t be able to access this without the Line Launcher, since stepping on the red Riddler pressure pads will close the trophy cage above. By using Catwoman you can collect this trophy much early. Hop onto the ceiling above the pressure pads and scurry towards the end of the cage. At the top platform Catwoman can collect both her trophy and Batman's trophy, providing you didn't somehow activate the red pressure pad. – thanks to Belthizor 23. By the waterside near the centre of Arkham City's north wall. Use the Batarang in time with each of the five Riddler marks. 24. In a passageway between two buildings west of Solomon Wayne Courthouse, protected by a locked TYGER panel and an electrified floor. 25. Inside the larger building west of Solomon Wayne Courthouse, which can be accessed through a destructible wall on the north-side wall. A powered gate must be opened with the REC before collecting the Riddler trophy. 26. Follow the road east of Solomon Wayne Courthouse's entrance. The Riddler trophy is inside a cage, which is restricted by the vent of hot air. 27. In the church behind the destructible wall of the second confessional booth. 28. In the church grapple on to the gargoyle above the entrance then drop down onto the edge to the left with a destructible wall. If you can’t manage this, return when you earn the Line Launcher. 29. Enter the bell tower and start climbing to the top. After taking the set of stairs at ground level and grappling up to the next level, turn around and find the Riddler trophy stuck to the wall. Use the Batclaw to collect it. 30. Northeast of the ACE Chemicals tower, in the centre of the roof inside a small structure with a destructible wall. 31. West of the ACE Chemicals tower is an alleyway opposite Gotham Casinos. Once you have the REC, use it to open the gate and collect the Riddler trophy inside. 32. Inside Solomon Wayne Courthouse, start heading downstairs at the back of the building then turn around. Use the Batclaw on the Riddler trophy above the doorway. 33. Inside the Solomon Wayne Courthouse, from the rear entrance to the courthouse throw a remote Batarang through the nearby electricity then guide it downstairs. Once there, navigate over the bars in the first room to hit the fusebox on the far wall. 34. In an alleyway southwest of Solomon Wayne Courthouse. You'll need to leap a chain link fence then slide underneath a small gap to collect it. 35. Slightly east of the Confiscated Goods Vault is a small chain cage, protected by land mines. The Riddler trophy is inside. 36. In the far northeast corner of Park Row, between its border with Amusement Mile. Use Freeze Grenades to create a platform near the trophy. Museum 1. At the entrance of the museum, jump left through the wooden panel. Quickly tap L2/LT to throw multiple Batarangs at the three Riddler marks to unlock the Riddler trophy. 2. At the very top of the trophy room is a platform you can grapple onto. The trophy is sat on top of here. 3. There's a destructible wall in the south of the trophy room area on the top floor. The Riddler trophy is on a set of crates inside. 4. Above the Scarface display in the trophy room is a vent. Use the Batclaw to dislodge it then climb through to the next corridor. The trophy is protected by a TYGER camera. 5. Slide under the barrier leading to the southwest corridor. A set of quarantine lasers will block entry to the trophy ahead, so use the upgraded Cryptographic Sequencer to unlock the bars. 6. In the corridor leading out of the trophy room, turn left and use the REC to open the gate. 7. Above the last Riddler trophy is a cage with an access grate. The trophy is inside here. 8. After surviving the Gladiator Pit and unlocking the gate you'll come to a lift powered by the REC. Before riding the lift, activate it so you can reach and destroy the destructible wall on the right to collect the Riddler trophy inside. 9. After riding the lift and accessing the floor above, look for a water cooling chamber on the wall. Use the Batclaw to wrench it open. 10. From the top of the Gladiator Pit guide a remote controlled Batarang through the electrical current and back around into the fusebox in the central corridor with the locked gate. 11. From the last trophy, smash through the window at the end of the corridor and walk around to collect the Riddler trophy. 12. Below the platform as you enter the torture chamber is a water cooling chamber. Drop onto the ice and use the Batclaw to open the vent. 13. In the northern corridor of the Torture Chamber is a REC-powered door. Activate and slide under. You only need to hit one of the Riddler marks, so use L2/LT to quickly fire Batarangs until you successfully hit an active button. 14. In the northeast corner of the Armory is a door locked by a panel on the left. Unlock it and collect the trophy sat on the floor. 15. Sitting inside the floor grates running along the south side of the Armory's ground floor. 16. Along the far west side of the Armory is a hidden corridor. In the north corner of this area is the Riddler trophy, blocked by hot air. 17. Underneath the central bridge of the Armory is a TYGER panel. You will need the upgraded Cryptographic Sequencer to reach it. 18. To the east of the bridge in the Armory is a set of destructible walls, with the Riddler trophy inside. 19. A frozen Riddler trophy sits in the northwest corner of the Torture Chamber. Return here once you have the Freeze Grenades to collect it. 20. Inside the chamber that was holding Mr Freeze. 21. In the northeast corner of the War Room, blocked by a blast of hot air. 22. Inside a small room connected to the bottom floor of the Iceberg Lounge is a small gap beneath a gate. You'll need to slide underneath once the mines have been dealt with. Wonder City 1. Quickly when entering the Collapsed Streets, look for a grapple point up above after the stream of hot air. 2. Just behind that hot air is another Riddler trophy. Stop the air and gain access to the trophy. 3. Jump through the glass window at the end of the first corridor. The trophy is inside here, but its cage will close whenever you enter. First, use explosive gel to destroy the left-hand destructible wall. Then make your way around the room so you can see through the now-open window and use the Batclaw to grab the trophy. 4. In the Collapsed Streets where you must navigate the drop with the line launcher, look to the south for a small room with a Riddler trophy. Use the line launcher to get in there.
On a ship close to the complete bridge going between the Industrial District and Amusement Mile, there is a small raised area on it. If you stop on this little platform and take out your Cryptographic Sequencer, you will start hacking something. This hack is very tough, but after you get it the trapdoor opens. When you go down you'll see hundreds of bugs scurrying around and a dead henchman. If you zoom in on the henchman he will move a little bit. To the right of the henchman is a clipboard with Dr. J Crane's name on it, and an order for several thousand of those bugs.
When you enter the Steel Mill, in the Manager's Office you will find Harley Quinn's attire from Batman: Arkham Asylum. Right next to it on the floor you will see a pregnancy test box that says "Fruitful Endeavour" and right next to it is the actual test that reads positive.
Behind the Monarch Theatre is the so called Crime Alley. Enter the alley andbehind the theatre to find the chalk outline of Bruce Wayne's dead parents. A touching moment can be had by pressing A nearby it to pay your respects. Disturbingly, Hugo Strange has also been there to leave you a message.