The Lost World – Jurassic Park (Saturn, PlayStation)

In this edition:

• I examined the password system for the 1997 game The Lost World: Jurassic Park in Ghidra, the reverse engineering tool.

• This allowed me to replicate it in Python and uncover some previously-unknown cheat codes. They enable a stage select screen, an invincibility mode, and two photo galleries.

• I also found hundreds of thousands of valid passwords (with duplicate effects) for then PlayStation version.

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

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.

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.

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

AXXY AYXY YYXY: Hunter gallery
AYXY XXZX ZZYY: Compy gallery
AYXY YYZY AYXY: Ending movie
AYYY XYXY YZYY: T-Rex enable

XAXY YYYY ZXYY: Unlock all stages
XXXX XXXX XXXX: Easy mode
XZXY XYYY ZXYY: Raptor gallery
YXXY XYYY AYXY: T-Rex gallery

YYXY AYXY YYXY: Invincibility*
YYXY ZXYY XZXY: Hunter enable
YYXY ZYYY ZXYY: Prey enable
YZAX YZAX YXAX: Stage select*

YZXY ZAXY AAXY: Prey gallery
ZAZY AXYY AZZY: Full arcade gallery*
ZXYY YZXY XYXY: Raptor enable
ZYAY AXXY XZAY: Limited Arcade gallery*

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 4 images; the full one shows 8.

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

The PlayStation version’s password system works differently. Instead of there being one password for each effect, there are many passwords that encode the same effect.

The game first encodes your button presses to numbers and stores them in an array: 00=Square, 01=X, 02=Circle, 03=Triangle. Then it computes a checksum: the 6th and 10th bytes are combined and checked against a combination of the other bytes. If they match, the password is good.

The rest of the password encodes your progress in the game and which settings you changed in the Options menu.

If you include all of the options and allow for duplicates, there are 380,160 valid passwords. Here are valid ones for each effect that aren’t published anywhere (to my knowledge). S is for Square, C is for Circle, X is for X, and T is for Triangle:

SSSS SSSC SSCS : Play as Hunter
SSSS SSSC STCX : Hunter gallery
SSSS SSSC XSCT : Play as Raptor
SSSS SSSC XCCX : Raptor gallery

SSSS SSSC TSCX : Play as Compy
SSSS SSST TTCX : Compy gallery
SSSS SSCS SSTT : Prey gallery
SSSS SSCS SCTX : Play as Prey

SSSS SSCS XSTC : T-Rex gallery
SSSS SSCS XCTS : Play as T-Rex

The code I used to generate these is here.

There’s also the Level Select password, which needs to be entered three times. It’s tracked separately, and doesn’t use the checksum system:

SXCT TXSC TCXS: Level select

For previous adventures in cracking password systems, see my articles on Three Dirty Dwarves, Ecco the Dolphin: Defender of the Future, and Burning Rangers.

Stay tuned for more reverse engineering articles! Upcoming topics:

• A candy-themed 3D platformer for PlayStation

• A prototype build of a Saturn game

• A candy-themed action game for GameCube

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