Expansion hack: Metal Black
Debug mode, invincibility, and more
The Saturn version of Metal Black is a port of the 1991 Taito arcade game. In its story, Earth is suffering under an uneasy truce with a hostile alien force. Our hero, John Ford, takes it upon himself to banish the aliens by commandeering an illegal space plane. Weirdly, the bad ending is good (Earth launches a strike against the aliens) and the good ending is bad (Earth gets broken in half).
Why am I writing about it? Alas, it’s not because there’s a prototype demo of it on Saturn Super Vol. 6 - that version sadly doesn’t have any additional files.
No, I’m writing about the final game’s heretofore undocumented DEBUG MODE. You can get a patch to enable it from SegaXtreme. Here’s a video!
Debug mode
The flag at 060a6f00 controls whether the special DEBUG MODE and ROUND SELECT items appear in the options menu.
Debug Mode changes a few things. Most notably, it gives you additional options on the pause menu - MUTEKI ON makes you invincible:
Additionally, you get extra controls:
X freezes and gameplay without bringing up the pause menu
Y advances frames slowly when you hold it
Z advances frames one by one when you press it
L shows some text information on the screen
R fast forwards the gameplay
C instantly kills you
That last one is really annoying! I’ve disabled it in my patch (see below).
The round select changes your starting stage. You can even pick the two bonus stages:
Technical details
I found the debug mode by searching for the string DEBUG in a save state - sometimes it’s that easy.
There’s no way to set the flag that enables the menu item, e.g. with a button code, so we have to patch the reads to it:
06014362 e001 # Read a constant 01 instead of the dynamic value
06013a72 ed01 # DittoOnce it’s enabled, you can toggle debug mode. This flips another flag at 060a6eff, so an alternative way of enabling debug controls is this Action Replay code:
360a6eff 0001To prevent the C button from killing you when you accidentally press it, I also disabled one check for the debug flag during normal gameplay:
0601e994 e000 # Read a constant 00 instead of the dynamic valueOne other note: this debug mode is very similar to the one present in Galactic Attack, a.k.a. Layer Section - it also enables Debug Mode and Round Select in the options menu, Muteki in the pause menu, and frame advance controls.
See TCRF on how to enable that one. This game was also developed by Ving and published by Taito; it seems there was some code reuse.
Outro
For more about Metal Black, see this characteristically great article at Hardcore Gaming 101. For other hidden debug modes, see:
Feel free to use this information and these screenshots elsewhere. Also, send me your suggestions for games to analyze next!