At specific locations in chapters 1, 2 and 4, you can find certain random, unmarked doors that secretly hide shops. Knock on the doors 3 times (tap your gamepad as if you are knocking) and you will see the screen shift for a short period of time Enter the following code (be quick, you only have a short window to do so) and you will be given the option of purchasing a reward for a (hefty) halo price. See guides for how to farm halos more easily These rewards range from top tier accessories, to hidden weapons, even to all the unlockable chararacters (both in campaign and tag climax). You can access them without needing the specific collectables or having to beat the difficulty mode/challenge to obtain them. Detailed is both the code and location of the door, its rewards and the halo price for purchase. Pictures are included as well. Note: The doors can only be activated if you do not already possess the reward.

Code	Effect
Balder (5 million Halos)	Chapter 4, Verse 6, first green door to the right when you kick down the large door to enter the night city.
Bracelet of Time (1 million Halos)	Chapter 1, Verse 1, two green doors found in the far left corner of in the central plaza area.
Chain Chomp (1 million Halos)	Chapter 1, after Verse 4 where you open the door, small bridge in alleyway before square leading to church square.
Climax Brace (2.5 million halos)	Chapter 1, Verse 1, brown door in the center right of the plaza area.
Climax Brace 2 (2.5 million Halos)	Chapter 1, the door right next to the climax Brace.
Eternal Testimony (2.5 million Halos)	Chapter 1, Verse 1, bigger brown door underneath the 2nd floor passageway center right of the plaza.
Jeanne Character (500K Halos)	Chapter 2, Verse 1, brown door to the right as soon as you start the Chapter.
Rodin Character (10 million Halos)	Chapter 4, right after Balders door and Loki cutscene, door is in a back alley next to crates.
Rodin Weapon (5 million Halos)	Chapter 1, the next door across from chain chomp, also on a small bridge.
Rosa Character (1 million Halos)	Chapter 2, green door a few passes past Jeannes door. Next to a green resturaunt menu on a tripod.
Up, Down, Up, Right, Left, X, B, Y, A	After knocking three times on the specified door, input the code to be taken to a purchase prompt.