Under the microscope: Puyo Puyo Tsuu (Saturn)

A moderately complicated cheat code entry system

In a previous edition, I wrote about how some Saturn games censor their high score screens. If you try to put your initials in as XXX or SEX, they’ll replace your entry with something else.

Puyo Puyo Tsuu, the falling block puzzle game from Compile, is one of these censorious games. It replaces naughty names with ARL, for Arle Nadja - the central character in the Puyo Puyo series.

Left: XXX gets the 3rd highest score. Right: ARL is shown at rank 3 instead.

The function at 0601a008 does this game’s sanitization. It loops through pairs of names, checking the player’s entry against the first item in each pair. If there’s a match, it substitutes the second item in the pair. This Python snippet demonstrates the logic:

ALL_SPECIAL_NAMES = [
  ('2RU', '2RU'), ('NAO', 'NAO'), ('MOT', 'MOT'), 
  ('TOM', 'TOM'), ('3KA', '3KA'), ('JNK', 'JNK'),
  ('SEX', 'ARL'), ('XXX', 'ARL'), ('XX ', 'ARL'),
  ('X X', 'ARL')
]

for i, (special_name, replacement_name) in enumerate(ALL_SPECIAL_NAMES):
    if player_name == special_name:
        player_name = replacement_name

We see the usual variations on SEX and XXX here, but also some unexpected items. The code checks for 2RU, NAO, MOT, TOM, 3KA, and JNK. However, it doesn’t censor them - it replaces them with themselves. What’s up with that?

The next bit of logic looks like this:

    if (i < 6) and ((p1_held_buttons & 0xff8) == 0xe48):
        special_name_effect = 1

For the six names above, the code sets a special value if a particular set of buttons is being held down. Like most Saturn games, Puyo Puyo Tsuu represents each controller button with a unique bitmask. This allows it to detect simultaneous button presses by checking for the logical OR of these masks.

Here, the target is the logical OR of the bitmasks for Start (0x800), A (0x400), C (0x200), X (0x40), and L (0x08). Hold those down to finish entering one of the special names, and the value at 0607a6ac will get updated.

That address gets read on the Options > Sound Test page, which has more held-button checking logic:

if sound_test_menu_cursor == 3:
    if (special_name_effect == 0) or ((p1_held_buttons & 0xff8) != 0xea0):
        play_sound(voice_sample_id)
    else:
        ... # Do something special

This check is for Start+A+C+Y+R, and it only executes when the cursor is on index 3 - the Voice item.

The Voice item highlighted on the Sound Test screen

Putting this all together, we have this three-step process:

1. Start a single player game. Accumulate enough points to get yourself on the high score screen.

2. Put in the initials 2RU. Enter the last character by pressing and holding Start+A+C+X+L until the screen fades out. (The initials NAO, MOT, TOM, 3KA, and JNK also work).

3. Return to the main menu, then navigate to Options > Sound Test. Highlight Voice and press Start+A+C+Y+R.

One of the ending sequences will start playing, followed by the staff credits.

The credits roll

The Voice sample you’ve selected affects which ending plays. So this is a hidden “Ending test” mode! There are four different ending sequences.

Left: Ending 00. Right: Ending 01.

Left: Ending 02. Right: Ending 03.

Here are my best guesses at what the special names above mean:

• 2RU: Yoshiaki Tsuruoka

• NAO: Naozumi Honma

• MOT: Motoyuki Kanayama

• TOM: Tomonori Minami

• 3KA: Toshio Akashi (maybe?)

• JNK: Kenji Kawakita (total shot in the dark)

If you can improve on these, do leave a comment.

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Outro

I can see why this Easter egg took more than 30 years to discover! For more on elaborate cheat code entry schemes, see my articles on Asuka 120% Limited BURNING Fest., Aero Elite: Combat Academy, Stunt GP, and Shining the Holy Ark.

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