Expansion hack: Far East of Eden - The Apocalypse IV
The debug menu in Tengai Makyou: Daiyon no Mokushiroku
Tengai Makyou: Daiyon no Mokushiroku, a.k.a. Far East of Eden: The Apocalypse IV is a 1997 RPG from Hudson and Red. It was a Japanese Saturn exclusive at the time, but eventually got released on the PlayStation Portable. The game is perhaps best known in the West for its charmingly inaccurate map of the United States.
Tengai Makyou has long been known to have a debug menu. According to TheMansour, who alerted me to it:
[The debug menu] doubles as a crash handler for when the game doesn't know which zone to load in the world map… But there's no easier way to open it.
This video from shows a method for accessing it, but it seems pretty cumbersome. Can we do better?
Yes! I’ve made a patch that will boot straight into the debug menu. Get it from SegaXtreme. Here’s a video of it in action:
This article will describe the debug menu’s features and the mechanics of the patch.
The debug menu
Most of the menu items do what you would expect from their names. AifPlay and CpkPlay refer to sound and video files, respectively.
Some are less comprehensible, but by selecting them you can get an idea of what they do: Test_S seems to be this menu itself. Test_F alters various flags. ChgDsk prompts you to insert Disc 2.
The flags in the FLAG_Global_Top are particularly interesting - check out the debug menu that you can pull up with the Z button:
Attr and NoAttr toggle collision. Time controls the time-of-day feature. EventN labels special tiles. Test warps you to a special room (see below).
Area and Rmap help you warp to specific parts of the game.
Some things don’t seem to work at all, like ChkP and 8255. It’s not clear what they are meant to do.
The coolest thing in the menu is called Test. This is a special room with non-playable characters. You can interact with them to perform various game functions. One shows you movie files, another lets you edit player parameters, and another lets you do a custom battle.
It’s sort of an alternative to the menu-driven interface from above, but it’s a bit more limited.
There are numerous options for testing sprites, and you can even swap out which characters are in your party.
In addition, the menu lets you test various aspects of the animation - some of the cels you see are unused in the game.
If you’re a fan of this game, I highly recommend checking this out: there’s a ton of stuff in here.
Technical details
Like a lot of games, Tengai Makyou uses numbered “modes” to determine which code to execute. When the game first boots, you’re in mode 00. When the opening movie plays, you’re in mode 08. The title screen is mode 2A, etc.
The “next mode” value is stored at 26011f5e, so if you set a write breakpoint for that address, you can switch modes arbitrarily. My patch changes the writes for the opening movie from 08 to 01, which causes the debug handler to pop up:
0604e3a 0001
This has the effect of keeping you in the debug menu even if one of your selections would cause the game to restart.
While we’re here, there are demos of this game on Saturn Super Vol. 11 and Tech Saturn 1997-02. They are from 1996-11-12, about a month before the final game (1996-12-08). You can access the menu on them, but since the demos are missing files you can’t do much. The main menu tells you different information, though;
Some of the features require you to change discs - those will prompt you when you select them. I checked the second disc to see if debug mode could be launched from it, but the answer seems to be no.
Outro
Many thanks to TheMansour for suggesting this hack and contributing screenshots and research for this article!
If suspect that some other game that has something hidden, point it out to me and I’ll probably look at it. For previous coverage of hidden debug modes, see the article on Shinobi Legions. I’ll have another one next week!