Under the microscope: Dungeon Master Nexus

Level select, noclip mode, and more

Dungeon Master Nexus was a Japanese Saturn exclusive, but through the magic of fan translation patches, you can play it in English.

This patch sparked some renewed interest in the game, leading Dungeon Master fan Blueskyrunner to start examining it in detail. He pointed out to me that there are some interesting strings on the disc image:

Suggestive strings as rendered by Ghidra

After some investigation, I found that this is part of a special cheat mode! To activate it, pause the game and then enter this button sequence:

L, R, X, Up,
C, Left, L, Right

This will bring up a debug menu. You can move between pages by pressing L and R:

The items are:

• MenuMode: Toggle this and press A to dismiss the debug menu.

• SuperMan: Unknown. It’s not invincibility — tell me if you know what it is!

• Report: Print out lots of debug information.

• Map_X: Move in the X direction.

• Map_Y: Move in the Y direction.

• CAM_Y: No apparent effect.

• Coli: Toggles collision. When it’s turned off, you can walk through walls.

• Level: Switch levels.

There are pages that have no menu listed. Don’t hit up or down; you’ll get stuck on them!

The Report option can really clutter up the screen, but the messages it prints out are pretty interesting:

The game checks for the code sequence in the function at 060100fa. Here’s Ghidra’s decompilation of the relevant section of that function, with my labels:

The button code sequence is at 06049538

I wonder what was on the pages that don’t work? I checked the demo version of Dungeon Master Nexus on Flash Sega Saturn Vol. 26, which uses a prerelease build (demo: 1998-01-14, final: 1998-02-03):

Remarkably, the code works! Alas, it has the same missing pages. You can probably disable collision to see more of the prototype level, however.

Debug mode on the prototype demo

If you’ve got an older prototype build of this game lying around, I’d be happy to analyze it…

Here’s a video of the debug features in action:

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Outro

For previous coverage of new cheat codes for old games, see:

• Sakura Wars

• Fighters Megamix

• Fighting Vipers

• Gex

• Solar Eclipse

• Gale Racer

• Shinobi Legions

• Three Dirty Dwarves

• Clockwork Knight 2

Many thanks to Blueskyrunner for the tip!