Expansion hack: Ms. Pac-Man: Maze Madness (Dreamcast, PlayStation)

Or, "Extending the demo: Ms. Pac-Man: Maze Madness (PlayStation)"

In this edition, I’m examining Ms. Pac-Man: Maze Madness. This game was developed and published by Namco Hometek in 2000. It’s based on an update to the classic Pac-Man gameplay – you guide Ms. Pac-Man through series of mazes with the usual pellets, bonus items, and ghosts. But there are lots of additions, like springs; powerups, and new types of enemies. All of the characters use 3D polygonal models.

I’ve created patches for three versions of this game:

• The Dreamcast version

• The PlayStation version

• The prerelease demo of the PlayStation version

The patches enable access to the hidden Level Select menu that’s described below. You can get them from GitHub! Read on for details about how they work.

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The Level Select menu

It’s well known that this game has a Sound Test that can be unlocked and accessed from the pause menu:

The Pause menu

However, it’s less well known that the game has a hidden Level Select that can transport you to any area in the game.

The Level Select menu

Some of the areas seem to be unused. When you choose one of these, Ms. Pac-Man will be stuck in the middle of some plane and unable to move anywhere:

Ms. Pac-Man stranded on some ice

If you choose one of the areas that represent the “end of level” scene, you’ll eventually be taken to a broken version of the title screen:

The title screen’s menu options seem to use the wrong labels

On the Dreamcast version, the levels with MP in the name don’t do anything. But on PlayStation, they take you into the multiplayer menu:

The multiplayer menu

There are some unfinished levels in the PlayStation version. These have basic background and grids with solid colors:

The gray and purple grid

There’s a prerelease demo disc that lets you access levels that don’t work in the final version. Some of them have corrupt textures, like 84-1:

Corrupt Ms. Pac-Man

Others change the color scheme of Ms. Pac-Man entirely:

Ms. Ashura?

I’ll leave the cataloging of which stages are used and unused to the fans of this game. Leave a comment if you find something interesting!

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Patch details

Action Replay hackers have noted that there are invisible items in the pause menu for this game. Here’s a screenshot from GameHacking.org that describes the ones for the PlayStation version:

Code by user SuperMoonKnight

Of these, only item 0x05 works in the Dreamcast version.

The game restricts access to the items beyond item 0x02 if the Sound Test hasn’t been unlocked. It restricts access past 0x03 if the Sound Test has been unlocked.

Here’s what Ghidra’s decompilation of the relevant logic looks like for the Dreamcast version (I’ve added function and variable labels):

  down_pressed = check_input_8c0d0e60(0x20);
  if (down_pressed != 0) {
    pause_cursor_8c175262 = pause_cursor_8c175262 + 1;
    end_animation_8c0a2360();
    if (unlocked_sound_test_8c23ed07 == '\0') {
      if (2 < (short)pause_cursor_8c175262) goto wrap_cursor_8c0b4a04;
    }
    else if (3 < (short)pause_cursor_8c175262) {
wrap_cursor_8c0b4a04:
      pause_cursor_8c175262 = 0;
    }
    play_sfx_8c0e8820(0x21,0);
  }

My patch alters this logic such that the unlocked_sound_test_8c23ed07 check always succeeds. Then it alters the jump table that determines what code executes after each item is selected.

Here’s the unaltered jump table in the Dreamcast version:

8c0b4b90 6aff  # 0x01, Back to Game
8c0b4b92 8401  # 0x01, Exit Stage
8c0b4b94 8400  # 0x02, Options
8c0b4b96 c400  # 0x03, Sound Test
8c0b4b98 4401  # 0x04, Show Level
8c0b4b9a e400  # 0x05, Level Select

The patch moves the target for item 0x05 into the slot for item 0x03. This turns the Sound Test into Level Select.

The patch also changes the Sound Test label string:

8c126b2c "Sound Test"

This makes a more descriptive name show up in the pause menu:

The updated pause menu

Similar tricks work for the PlayStation versions of the game.

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Outro

Interestingly, a very similar level select menu appears in Pac-Man World. That has been documented by others – see this article on The Cutting Room Floor for details.

A Nintendo 64 version of Ms. Pac-Man Maze Madness was also published in 2000. Its code is clearly derived from the same source as the PlayStation and Dreamcast versions, but it doesn’t have any of the hidden items on the pause menu. I’m not sure why!

For other entries in the Expansion Hack series, see my archive here at Substack. I’ll be back with more soon.

Logo by Ashlyn Anstee