In Jersey Devil, you play as a masked vigilante roaming the streets of Jersey City (not that one), chasing down evil mutant vegetables. The manual explains the situation:
Galloping garlic, killer cabbages, and pumpkin ghouls chase down their shrieking victims. Innocent people are being dragged from their own neighborhoods. It's not just vegetarians, every human in town is being stalked and snatched.
The opening animation depicts these events, Jersey Devil’s origin story, and the evolution of Jersey Town into Jersey City. There’s a lot going on.
There’s also a lot going on in the game. The HUD keeps track of how much health and how many lives you have. But it also indicates how many pumpkins you’ve collected, how many Nitro boxes you’ve destroyed, how much Nitro power you have, and how many KNARF tokens you’ve picked up:
There is comparatively little going on with cheat codes, however. GameFAQs, IGN, and company just list one: pressing Triangle, X, Triangle, Square, Square, Circle during gameplay gives you 99 lives.
Good news: there are six previously unreported cheat codes! I’ll describe each of them below, and detail how the game checks for them.
Restore health
If you’re running low on health, enter this sequence during gameplay:
Triangle, Triangle, Triangle, R2, Square, Circle, Square, R2Your health bar refill to its maximum value:
Get nitro potion
As the manual says, you need to “Blow up a Boss Level with a Nitro Bottle to increase Jersey Devil’s Nitro power.”
To get such a bottle, enter this sequence during gameplay:
Square, Circle, X, Triangle, Circle, Square, X, Triangle, CircleThe Nitro Boxes counter in the bottom-left corner will change to show the bottle:
Get nitro power
This sequence will increase nitro power directly:
X, Circle, Triangle, X, Circle, Square, Square, TriangleThat gauge is at the bottom-right of the HUD:
Death animation
To see Jersey Devil die, hold these buttons during gameplay:
L2+R2+Circle+TriangleThe stage will restart, but you won’t actually lose a life.
Five KNARF tokens
The manual says “Collect KNARF tokens to get the Golden K that opens locked doors.” You can skip the collection and get the Golden K directly by entering this sequence:
Circle, Triangle, Circle, X, Triangle, Triangle, Circle, X, R2The Golden K will be displayed in the bottom-center on the HUD:
Show credits
To see the end credits, enter this sequence during gameplay:
Triangle, Triangle, X, Triangle, Circle, Triangle, Triangle, Triangle
Technical details
I tracked these cheats down by first checking GameHacking.org. That told me that the number of lives you currently have is stored in memory at at 80010043.
Then I loaded a memory snapshot from the game into Ghidra. I used the MIPS:LE:32:default spec, which works for PlayStation, and adjusted the base address to match the console's memory map (starting at 80000000).
That allowed me to locate the places where the game writes to the “lives” address. The code associated with the already-known “99 lives” cheat effect looks like this:
80029da4 li v0, 0x63 # Load an immediate 99 into v0
80029da8 lui at, 0x8001 # Load 80010000 into at
80029dac sb v0, 0x43(at) # Store the 99 in v0 into 80010043Scrolling up from that leads to the function at 80029b64. It refers to data at 8004a9b8 that has this structure:
Two bytes: The index of the cheat code
Two bytes: The number of correct button presses you’ve made
20 bytes: The bit patterns for each button in the cheat code
The “99 lives” button patterns are:
8004a9bc 1000 # Triangle
8004a9be 4000 # Circle
8004a9c0 1000 # Triangle
8004a9c2 8000 # Square
8004a9c4 8000 # Square
8004a9c6 2000 # Circle
8004a9c8 0000 # End of codeWhen you get a button press right, the counter associated with the cheat code is incremented. Once you complete the sequence, the game reads the code index and applies the corresponding effect.
Outro
As always, feel free to use the information and screenshots in this article on your favorite fan site, wiki, or similar. Also, leave a comment if you can think of any games that might have hidden secrets like this one did.
For more cheat code discoveries, see my archive. I’ll be back next week with more!
