Under the Microscope: The Lost World – Jurassic Park

In this edition:

• I reverse engineered the password system The Lost World: Jurassic Park, revealing some long-unknown cheat codes.
• The new codes enable a stage select screen, an invincibility mode, and two photo galleries.

Read on for the details! Here’s a video showing some of the new stuff:

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Intro

According to EGM 93, Dreamworks Interactive was very invested in making this adaptation of the Jurassic Park sequel successful, and spent lots of time and resources on its graphics and animation. Their team focused on the PlayStation game and farmed out the Saturn port to Sega and Appaloosa Interactive.

Both the PlayStation and Saturn versions have you input 12-character “DNA sequences” as passwords. The character choices match the controller buttons for the console you’re playing: Square, X, Circle, and Triangle on PlayStation; A, X, Y, and Z on Saturn.

Cheat code repositories have had passwords listed for both versions of the game since the 1990s. But they don’t match up — you can’t translate Square to A, Circle to B, or Triangle to C, for example. What’s going on? I decided to take a look.

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The Saturn version: technical details

When you’re on the Password screen, the code loaded at 06071760 (NTSC-U version) checks for button presses. Those get stored to an input buffer, and then checked for validity after you enter the 12th character.

The input buffer starts with the value 060FFB74 (this looks like a pointer to the Saturn HWRAM area, but it’s not). Each letter flips some of the buffer’s bits by applying an OR mask followed by an AND mask. The mask bits depend on what position the letter is in. Here’s the OR mask table:

And the AND mask table:

After applying the masks to each character position, the resultant bits are then validated by comparing them to 4-byte substrings (encoded with ASCII, except for the underscores, which are zeros) of this phrase:

THREEDIRTYDWARVESRULEZ GREGCORTHAGTACONIC199____AxCvUkSngGeGREGE

Three Dirty Dwarves! This is another Appaloosa Interactive game whose password system I cracked in a previous article.

All we need to do is check all of the 12-character strings that use A, X, Y, and Z (16,777,216 of them) to see which ones are valid. I wrote this script to do the job.

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The Saturn version: results

Here’s the full list of passwords recognized by the Saturn version:

Four of these seem to be new!

The Invincibility code, as you might have guessed from the name, makes you invincible. It also displays some text that says DEBUG:INV text on the Options screen when it’s active:

The Stage select code enables a screen that’s different from the one in the Options menu:

The Full arcade gallery and Limited arcade gallery codes has pictures of another game called The Lost World: Jurassic Park (this one was produced by Sega). The limited gallery has four images; the full one shows eight.

Did anybody know about these? As far as I can tell, this has remained secret for 28 years.

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Outro

For more on The Lost World, see Rings of Saturn blog — I also have an explanation of the PlayStation version’s password system there.

And for more Saturn hacks and cheats, see my archive here at SHIRO!.