In this edition:

• Impact Racing has a hidden debug mode that’s really cool. You can tweak car settings, track parameters, and more.
• It’s already been documented for the PlayStation version of the game, but the Saturn version hasn’t been unlocked.
• I’ve created a patch to make it accessible from the Saturn version’s main menu.

Get the patch to enable Debug Mode from SegaXtreme .

Intro

Impact Racing is a combination racing / combat game from Funcom Dublin. It came out for the PlayStation and Saturn in 1996. It’s reasonably competent, I guess, but is it anybody’s favorite game?

It came to my attention because of its debug mode. The PlayStation version is known to have a cool hidden menu that lets you adjust different aspects of the cars, tracks, gameplay and more.

So I was curious about whether that menu existed on the Saturn version. A quick check of the game binary showed the strings for it, but can it be accessed? I found a hint on the GameFAQs board for the game:

Subject : Debug Mode Found…
Date : 2010-09-08
User : Memorize99
Message : By me. Here’s an image. More info later, I’m sleepy…

Alas, the image link is broken! Later in the thread, the same user posts more information:

Debug Mode replaces Password on the Main Menu
D012BD24 0002
3012BD24 0004

The code works the first time you boot the game. After entering and exiting the Debug Menu, the code will no longer work. This is because the address to access the menu changes every single time you exit the menu. I tracked around eight different addresses before stopping.

It’s not quite this xkcd , but it’s close:

I decided to solve the rest of the mystery.

Debug Mode

Using the access method above, we can at least see that the Saturn menu is a bit different from the PlayStation version. The View VRAM option, is missing, for example.

You can navigate to different menu items with Up and Down on the D-pad, but you need to use L and R to change values. X and Z will change the values in larger increments.

Interestingly, the cars in the Debug menu have different names from the rest of the game. The first one is called VIPER2 in the menu and AR. 12 on the select screen.

The TWEAK MYSTERY option is referring to the bonus cars that appear on occasion:

I couldn’t see a difference with any of the fog settings:

You can see more of the screens from the PlayStation version on TCRF .

Technical details

It’s helpful when games use fonts to render ASCII text, rather than representing text in graphics. You can just search the binary for interesting strings like DEBUG MODE .

In Impact Racing , there’s a reference to the DEBUG MODE string at 0607b99c . It’s just after the other strings for the mode select menu:

NEW GAME , LOAD GAME , PASSWORD , and OPTIONS all have an associated 0050 parameter. DEBUG MODE has 0850 . The 08 seems to be a disable flag: if we change it to match the other strings…

Bingo. It seems like the disable value is hardcoded; there’s no way to change it from within the game. We’ll change what gets written with this patch:

06022dc0 0009

This is close to what the Action Replay code for PlayStation is doing also.

Outro

The GameFAQs user who posted the partial access method above is Mezmorize99, proprietor of ClassicGameHacking.com and YouTube.com/DreamcastVideos . Neither page has had recent activity, but there’s lots of worthwhile content on both of them.

If you are Mezmorize99, or can put me in touch with Mezmorize99, do reach out! I’d like to share the good news that the case has finally been solved.

Thanks for reading! Check out my Rings of Saturn blog for more adventures in retro game reverse engineering.

	Bo Bayles
		Rings of Saturn: 32bits.substack.com