Secrets 3-Minute Battle Mode Play the China-town level after getting the Katar.
Climb up the Chinese house that has the huge flame on the porch. When you are there, someone will surprise attack you (well, it won't be a surprize now, lol). Kill him and go to the opposite side of the part you climbed up to.
Go to the back of the house, but stay on the balcony. Jump to the building on the far side (all the way down, as far as you can see) and look around for another piece of paper. Walk into it, and you will unlock the 3 minute battle mode option.
Unlockables Twin Daggers To gain the Twin Dagger weapons complete the game on any difficulty then save after the credits. Load that game and they will be on EOE when you start. Best weapon(s) in the game.
Boss Battle Mode Play the final level, Wisdom Headquarters, and advance until you have activated the main elevator.
Go to the library (located on the unrestricted side) and go up the stairs. After you've activated the main elevator, the door at the top opens. Proceed up the stairs and out onto the balcony. Jump across onto the chandelier, then onto the other balcony, and enter the room on the other side.
In the room, there are two enemies that can be easily defeated along with the third and final piece of paper in the game. Retrieve the piece of paper and letters will come on the screen telling you that you've unlocked Boss Battle Mode in the Bonus menu. You can access this mode by entering "Bonus" on the main screen and entering your file.
Survival Mode Play level 1 and go through the subway when you need to get both Legacy Drives for the Lightning Rod. When you get out on the other side, go into the alley that has the fence with a junkyard on the other side. Walk up to the fence. Press Triangle when equipped with the Lightning Rod and quickly change to your hands to grab on to the top of the fence.
Jump over to the other side, then go to the wall that has the ladder against it. Climb the ladder and get up to the top of the building. Once there, you will find a piece of paper hovering above the ground. Walk into that piece of paper.
A message stating that survival mode has been unlocked will appear. Save the game, then enter the bonus option at the main menu to access the new option.
