Extending the demo: Motor Toon Grand Prix 2 (PlayStation)

An early look at the Gran Turismo team's second cartoon racer

In this edition:

• There’s a preview of Motor Toon Grand Prix 2 on the DemoDemo PlayStation Vol. 16 disc.

• Normally it lets you play as one character in one mode on one course, but the demo limitations are superficial – there’s data for all of the characters, most of the modes, and an extra course on the disc.

• I’ve made a patch that allows you to explore this pre-final build. It’s from more than 3 months before the final one, and differs in several ways – some of the characters even have different names.

Get the patch from GitHub! Details are below.

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Build differences

Without any modifications, you can see that the demo version of Motor Toon Grand Prix 2 is different from the final version. Its title screen (shown above) doesn’t match, for example.

The final version’s title screen

You can also see that the main menu is missing some elements. Some are greyed out due to demo restrictions, but Options and Goodies are missing entirely:

Left: The prototype demo. Right: The final version.

Furthermore, you can see that three characters have different names in the demo build: Vanity is “Speed Lady,” Billy the Tough is “Black Knight,” and Ching Tong Shang is “Mad Storker.”

You need the patch to actually see the characters, however. With it applied, you can see that their 3D models are more or less the same. There are some differences in lighting, though – the final version’s models are brighter.

Left: The prototype demo. Right: The final version.

Some of the character controls are different in the demo build. With the patch, it’s clear that Vanity isn’t fully implemented – she’s missing some animations, and her handling is much less responsive than it is in the final version.

Left: In the demo, Vanity doesn’t lean over while turning. Right: Her movements are very exaggerated in the final version.

Here are some more things I noticed:

• All of the HUD elements got moved around and redesigned in between the demo and final builds.

• In Free Run mode, the demo does a 3-2-1 countdown. The final version doesn’t.

• If you fall out of bounds, the final version shows a message like “I will rescue you!” The demo doesn’t.

• The available zoom levels differ quite a bit between the demo and the final version.

If you spot other things, leave a note in the comments.

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Patch details

The menu restrictions in this game are fairly easy to lift. Each menu item is rendered according to data structures that look like this:

• 1 byte: Index. The first menu item is 0x00, the second is 0x01, etc.

• 1 byte: Status. The greyed out items are 0x00; the enabled ones are 0x01.

• 1 byte: Style. 0x00 is normal; 0x01 is small; 0x02 is inverted colors.

• 2 bytes: Horizontal position.

• 2 bytes: Vertical position.

• 4 bytes: Pointer to the string with the item’s text.

The main menu’s array of structs starts at 8006c654. You can re-enable the greyed out elements by changing their Status byte to 0x01. The data for the other menus is nearby in the game data.

Manipulating the status, style, and position of the “Single Race” menu item

My patch changes the menu data such that:

• The Single Race, Time Attack, and Two Players Battle modes are all enabled.

• All seven extra characters are enabled.

• The extra course, Toon Island II, is enabled.

Normally, the demo kicks you out after five minutes. You get this Coming Soon! screen before it ends:

Here is part of Ghidra’s decompilation of the function at 8002807c. I’ve added function and variable labels to show how the “exit demo” logic works:

    /* Pressing Select + Start exits the demo*/
    p1_button_1 = get_input_8004b0a4(0);
    p2_button_1 = get_input_8004b0a4(1);
    if (((p2_button_1 | p1_button_1) & 0x900) == 0x900) {
      exit_handler_80010640();
    }
    /* After 18,000 ticks (5 minutes), the demo exits */
    timer_1 = get_timer_800432a0();
    if (17999 < timer_1) {
      exit_handler_80010640();
    }

My patch gets rid of the timer check that tracks how long you’ve been playing.

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Outro

Motor Toon Grand Prix II was released in the United States as Motor Toon Grand Prix. The Western version removes one of the unlockable things in the Goodies menu: a special mode with notes from the development team.

One of those notes is from the game’s director, Kazunori Yamauchi. He describes trying to improve on the first Motor Toon game by using the PlayStation hardware to generate cartoon-y visual effects. Then he teases his team’s next project: an ultra-realistic racing game. That game turned out to be Gran Turismo.

Yamauchi’s note. You have to complete Championship mode on the highest difficulty level to access it.

So this early look at a goofy cartoon racer turns out to be part of the legacy of one of the most iconic PlayStation games. Cool!

Logo by Ashlyn Anstee

Rings of Saturn will return soon with more retro game reverse engineering discoveries. Check out the archive for similar demo liberation patches in the meantime.