Under the microscope: Shinobi Legions

A debug mode cheat code that stayed hidden for a pretty good reason

Here are instructions for entering a cheat code in Shinobi Legions (a.k.a. Shinobi X, a.k.a Shin Shinobi Den). I swear I’m not making these up:

• Go to the Options screen

• Navigate to Music and select Stage 2-3

• Navigate to S.E. and select 06

• Navigate to Audio, hold L, and put in the 40 button sequence shown below

• Exit the Options screen and start a new game

• Press start to pause, and then hold R

The button sequence

That’s a lot to do, but it’s worth it! Your reward is a debug menu with several cool features. In addition, you also get free movement and the ability to do special moves any time.

Here’s a video to prove that it works:

If you’d rather not attempt to enter such a long code, here’s a patch you can use to play with debug mode enabled by default.

Below is more information on what debug mode does, and technical details on how the code works.

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Debug mode features

Most of the features listed on the menu are straightforward: Invincible makes you invincible, Stage lets you change stages, Shou credit is the number of lives you have, etc.

Debug Information: it shows you details about your position, the animations being displayed, what the sound system is doing, and more. It also displays hit boxes for the things you can interact with.

Debug Information and hit boxes

Ninjutu Name: it enables special moves. You can perform the selected move at any time by holding L and pressing X.

Summoning helpers with the Ninjutu Name option

Bunshin makes shadow versions of yourself take damage for a while. Rairyu summons a dragon to hit your enemies with lightning. Bishamon calls forth a statue warrior to attack enemies for you.

Zoom rate: I’m not sure what this does. Tell me if you do!

Free movement: You can reposition Shou by holding R+Z and then moving the D-pad. You can’t go through walls, but you can attack while moving in mid-air.

Flying through the air with R+Z.

Disable collision: If you hold R+Y, you can go through solid surfaces. But you have to be careful - unless you’re also holding Z, gravity applies and you’ll fall through the floor and die.

Flying through walls with R+X+Z

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The technical details

We’ll examine the PAL version here, because it has better music¹. The debug code also works on the NTSC-U version, and I imagine on the NTSC-J version too.

The usual technique of diffing memory snapshots reveals where the game stores controller input. Setting read breakpoints for those locations directs us to a function I call write_button_history (at 06042310). It records our button presses to a buffer that starts at 060dd0b4.

If we check the references to that buffer, we’ll find a function that I call check_button_code at 0604234c. This compares our button history to a known sequence.

Shinobi Legions uses this encoding scheme for buttons:

If we look at the things that call check_button_code, we’ll find that it’s called with several different parameters. The first is:

0200  # C button
0040  # X button
0100  # B button
0020  # Y button
0400  # A button
0010  # Z button
0800  # Start button

This matches the View all full motion videos code that’s been known for ages². Similarly, by examining the other calls to check_button_code, we’ll find other known cheats:

• 99 lives (060439b4): A, Z, B, Y, C, X Start

• One hit death (060438fa): A, B, C, B, A, Start

• 999 knives (060439b4): C, A, B

And then there’s the monster 40 button sequence from above. But where do you enter it?

The call for the 999 knives code provides a clue. For that one you have to be on the Options screen, highlighting the Knives item, and holding L+R. The call for the debug code is in the same neighborhood, in the section for Audio. It starts at 06040e7c and translates to something like this in pseudo-Python:

# Check for the Audio item
if menu_index != 5:
    return 0

# Check for the right music selection
if music_selected != 8:
    return 0

# Check for the right sound selection
if sound_selected != 6:
    return 0

# Check for L being held
if p1_held & 0x0088 == 0x0008:
    write_button_history()

# Check the button history buffer. If it matches
# the code sequence, play a sound.
if check_button_code(DEBUG_BUTTON_SEQUENCE) == 1:
    play_sfx(0x0108)
    return 1

return 0

I have no idea why they made this so involved! I kind of wonder whether this whole thing was put here by Tose for me to find 29 years later.

The Options screen, all ready for the Debug mode code to be entered.

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Outro

Feel free to add this information and use these screenshots elsewhere - if you update TCRF and Sega Retro, I won’t have to!

For previous coverage of undiscovered cheat codes, see:

• Three Dirty Dwarves

• Clockwork Knight 2

Also, send me suggestions - what games do you think have hidden secrets like this? I’m @memory_fallen on X/Twitter.

1. Thanks to Richard Jacques for that!

2. This one doesn’t work on the NTSC-U version because it lacks the opening FMV.