Expansion hack: G Vector

Making the impossible, possible

Mar 19, 2025

In this edition:

I found some previously-unknown cheat codes for the Saturn game G Vector, the 3D shooter. They give you extra modes, invincibility, a new character, and more!
But they’re either very hard or actually impossible to enter.
So I made a patch that makes their effects easily accessible.

The codes are explained below. You can get the patch from SegaXtreme.

Intro

Soft Office didn’t have a very long run. They put out three games: Daibouken: Saint Elmos no Kiseki, Pastel Muses, and G Vector. The first two had both Saturn and PlayStation editions, but the last one was a Saturn exclusive. All three seem to have received middling reviews.

G Vector is a 3D shooting game, and it’s got a reputation for being very challenging. A button code for extra credits has long been known1, which helps. But unless you’re a skilled player (or able to use Action Replay), you probably haven’t seen the later stages.

I started looking around, and was pleased to find a batch of cheat codes for this game. But entering them is a also very challenging, and in some cases actually impossible! I decided to patch the game to make their effects accessible.

Below are the details of how the cheat codes operate in the unmodified game, and what I changed in my patch.

Extra options

The instructions are:

When the Sega logo appears, start holding A.
Release it when the Soft Office screen finishes fading in, then switch to holding B.
Just before the Soft Office screen starts fading out, switch to holding C.

Hold A, then B, then C. Good luck on the timing.

The timing on the switch to C is very finicky, though - I think it has to be frame perfect. Even when guided by the debugger, I have trouble pulling it off.

Once you get it, these are the extra options:

Stage: pick a stage and press A to start playing it.
Exselect: During gameplay, hold L and press R to skip to the next stage (or hold R and press L to restart the current stage).
Pause CMR: When paused, the camera will rotate around your ship.
Disp Tama: Hides the pause menu when set to on.
Muteki: Invincibility. Your score will not be recorded, however.

Nagameru mode

The instructions are:

When the Sega logo appears, start holding A+Z.
Release it when the Soft Office screen first starts fading in, switch to holding B+R.

The timing here is somewhat more forgiving.

Nagameru means something like “look” or “watch”

Nagemeru mode lets you replay stages you’ve already completed. During the replays you’re invincible, and your performance isn’t scored.

An animal character?

The function at 06004dd8 checks a flag at 0606efcc. If it’s not set, the normal 3D model file (MYSHIP.3D) gets loaded. If it is set, a different file (PUCHA.3D) gets loaded instead.

This lets you fly a little cat animal instead of the spaceship! Or is he a tanuki?

I’m not sure if this is supposed to be a recognizable character — is “Pucha” Soft Office’s mascot? The “Pucha” flag is set after you enter a button sequence on the title screen:

Up+A, Right+B, Down+C, Left+X, Up+Y, Z, Up+Down

But here’s what’s weird: you can’t actually enter that! The Saturn control pads don’t let you put in Up and Down at the same time. Furthermore, even if you do enter it (maybe with the Saturn keyboard?), the game immediately unsets the flag afterward. I have no idea why!

Technical details, further mysteries

The function at 06004614 checks which buttons you’re holding during the Soft Office screen. It sets or clears flags accordingly:

060650dc  # Nagameru flag
0606c443  # Extra Option flag

The “Pucha” code is one of several that are checked by the title screen. Two of them actually work:

Nine credits   : Up, Up, Down, Down, Left, Right, Left, Right, A, B, C
Show staff roll: Up+A, Right+B, Down+C, Left+X, Up+Y, Z

There are three others that are either impossible to enter or don’t do anything:

Player 2 debug controls:
Up, Up, Down, Down,
Left, Right, Left, Right,
Left+A, Right+C, Down+B, Up+Y,
Left+X, Right+Z

Extra options (alternate):
Up, Up, Down, Down,
Left, Right, Left, Right,
Up+Down+Left+Right

Unknown 2 (probably nothing):
Up+Down, Up+Down, Right+Left, Right+Left

Player 2 Debug Controls look cool, but they’re hard to actually use. When the flag at 0606efc9 is set, you can press start on controller 2 to get this menu. L and R navigate the options. You can mostly mess with the camera:

The button sequences are stored starting at 060662e4. Each button corresponds to a two byte value, and combinations of buttons have those values OR-ed together (example: up is 1000 and A is 0400, so Up+A is 1400).

In my patch, I remapped the title screen codes as follows:

Nine credits: A, Start.
Debug controls: B, Start. Then press controller 2 Start during gameplay.
Unlock extra options: C, Start. Then let the title screen time out and come back. The menu item will be invisible, but it’s the last one.
Unlock Nagameru: L, Start. Then let the title screen time out and come back.
R, Start: Play as Pucha.
Z, Start: Show the staff roll.

Outro

This was a strange one — why so many unused cheats? Tell me if you have seen the cat / tanuki character anywhere else!

For other articles on undiscovered cheat codes, see my archive.

Nine credits: Up, Up, Down, Down, Left, Right, Left, Right, A, B,C at the title screen.

Rings of Saturn

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