Under the Microscope: Off-World Interceptor Extreme

In this edition:

I found some cheat codes for Off-World Interceptor Extreme that have stayed hidden for 29 years.
The codes also work on the the original 3DO version, Off-World Interceptor.
And a subset also work on the PlayStation port, too.

I found these by examining memory snapshots in Ghidra — technical details are below. Here are the codes, which are entered at the Options screen:

Intro

A while back we looked at Solar Eclipse (a.k.a. Titan Wars), a 1995 Crystal Dynamics game that features live action cutscenes that look like they’re from a low-budget sci-fi show. Off-World Interceptor is another one of those.

Unlike Solar Eclipse, Titan Wars doesn’t take itself seriously: it’s got the low-budget sci-fi show cut scenes, yes, but it’s also got shadowy figures making fun of them the whole time, a la Mystery Science Theatre 3000.

When I looked into Solar Eclipse, I found a boat load of cheat codes. But according to various Internet sources, Off-World Interceptor only has one. Is that right?

It’s not! I found several new ones. They’re all entered on the Options screen, which you can access before the game starts or from the pause screen.

You have to be careful about which item you start on, because if you land on EXIT and press A or C, you really will exit, even if you’re in the middle of entering a code. On the Saturn and PlayStation versions, you’ll hear the one of the voice clips (like Missile! or Plasma!) when a code is entered correctly.

I’ll list the Saturn sequences below. For 3DO, replace Start with P. For PlayStation, replace A with Square; B with X; and C with Circle.

Level select

This one changes your starting level for Story mode. After entering it, highlight the EXIT item on the options screen and use the D-pad to change the level number. It’s available on all three systems.

Left, Right, A+B+C, Up, Left, Right, A+B+C, Down, Start

Acid mode

This code makes the screen tint change. It’s the same visual effect as the air strike, but it keeps going. I’m not sure why you would want this! It’s available on 3DO and Saturn.

L+R+Left, Left, L+R+Left, Left, Start

Show hit boxes

Rectangles are drawn around your vehicle and objects you can interact with. It’s available on 3DO and Saturn.

L+R, R+A, A+B, B+C, L+C, L+R

Unlimited time

Normally when you run out of time, the level ends with the Purge Overkill message. This code lets you keep playing indefinitely. It’s available on all three systems.

Press L 23 times in a row, then press A+B+C

Maximum money

This is the code that was already known for this game. It gives you $9,999,900 to spend on in-game items. It’s available on all three systems.

Repeat the sequence A, B, C six times; then press L

Credits

They seem to have had a good time making this game. There are lots of pictures of the production staff goofing off. One of the pictures gives you the “maximum money” cheat code, which I suppose is how people figured out that one.

The code seems to be available on all three systems, but I couldn’t get it to work on PlayStation.

A, Up+A, B, A, Down+A, Up+C, Up+C, A, X, X

Invincibility

You have to put this one in before the level starts. Your vehicle will glow and you won’t take damage. This code works on all three systems.

Right, Right, Left, Left, Left, A

Powered up weapons

If you put this in on the Options screen before starting the game, you’ll begin playing with the powered up version of your main weapon. This code works on all three systems.

Left, Down, Right, A, Left, Down, Right, B, Left, Down, Right, C

Switch camera modes

On Saturn and PlayStation, this feature is enabled by default, so the code does nothing. For 3DO, press LS+A+B to switch between Battle-Cam and Chase Cam.

Down, Down, Down, Down, Right, Right, Right, Right, A

Technical details: code storage

On 3DO, the Options screen uses the function loaded to 000b1a0c to check for the codes above. It looks at the data structure at 000d08ac, which has a bit code index, a delimiter (value 0), the sequence of buttons, and another delimiter.

Here’s how the long-known “maximum money” sequence is encoded:

0000 0005: The code index
0000 0000: Delimiter
0000 0001: “A” button
0000 0002: “B” button
0000 0004: “C” button
(repeat A, B, and C six times)
0000 0008: “L” button
0000 0000: Delimiter

The full set of buttons is (3DO / Saturn / PlayStation):

0000 0001: A / A / Square
0000 0002: B / B / X
0000 0004: C / C / Circle
0000 0008: LS / L / L1
0000 0010: RS / R / R1

0000 0020: Up
0000 0040: Down
0000 0080: Left

0000 0100: Right
0000 0200: P / Start / Start
0000 0400: X / X / Select

These can be OR-ed together to indicate multiple buttons. For example, A+B+C is 0000 0007.

How is it that I located these, you ask? I compared compared memory snapshots from before and after entering the known code, and used Ghidra to follow the references to the values that changed. That led me to…

Technical details: configuration flags

Entering a code successfully sets one of the bits at 000cf3d8 (0025c784 on Saturn, 800a8bc0 on PlayStation), so if you can edit memory, you can skip entering codes by adjusting the value at that address.

There are more effects than just the ones enabled by the codes. The 3DO version has some plain text that seems to be associated with command line parameters that explains what most of the fields do:

0000 0001: Shut off sky draw ("SKY")
0000 0002: Start level immediately ("PLAY")
0000 0004: Activate MAGIC-CAM (tm) ("MAG")
0000 0008: Shut off HUD ("HUD")

0000 0010: No sound effects
0000 0020: No music
0000 0040: Unknown effect ("XXXX")
0000 0080: Show object position and collision crosshairs ("SHOW", code 04)

0000 0100: Try to get player car configuration from CAR.TXT ("CAR")
0000 0200: Turn on diagnostic messages ("MSGS")
0000 0400: For fun, -- change colors when playing ("ACID", code 03)
0000 0800: Show HERTZ, CTIME, and DT ("FPS", 3DO only)

0000 1000: Don't draw car images ("NCAR")
0000 2000: Don't do daemon tick ("NTIK")
0000 4000: Now you're invulnerable! ("SUPR", code 08)
0000 8000: Maximum money ("CASH", code 05)

0001 0000: Unlimited time ("TIME", code 06)
0002 0000: Always have powered up car ("POWR", code 02)
0004 0000: Turn on level select easter egg ("LEVS", code 00)
0008 0000: Never try to play FMVs ("FMV")

0010 0000: Taking finger off accelerator causes car to brake ("BRAK")
0020 0000: Go directly to credits ("CRED", code 07)
0040 0000: Allow camera switching ("CAM", code 01)
0080 0000: ?

1000 0000: Debug stats (Saturn only)

The “Magic Camera” allows you to arbitrarily move the camera.

Gex, also from Crystal Dynamics, had similar command line helper text.

Outro

For more coverage of previously-undocumented cheat codes, see my archive. What else should I be looking at? Send me your suggestions!

I’ll be back next week with a treat for Dreamcast fans…

* This post is syndicated from Rings of Saturn, Bo’s reverse engineering blog.