Under the microscope: Gex
Exploring the quippy mascot platformer
The Gex story, as told by the manual, is really something1. It goes on for four pages, and involves Gex losing a parent, becoming a gigolo, inheriting billions (from his uncle, the original Izod model), and ultimately getting sucked into his television.
The Saturn version of Gex is, of course, a port of the 3DO original. It’s got a bunch of well-known cheat codes and some bonus levels that the developers sneaked into the game2.
The 3DO version is the most complete, and also the one with the most unused stuff hiding out on the disc. But what might be hiding on the Saturn version? I decided to investigate…
The main level select code
When you’re on one of the overworld screens, press Start. Then hold R and press this sequence of buttons:
(Holding R) Left, Right L, Start, Left, A, Y, A, Up, Y
You’ll be taken to the primary level select screen from the 3DO version. This one lets you choose the normal levels (excluding the Planet X ones) and some non-levels like the Game Over screen.
The “Planet X” level select code
At the title screen, press Start to bring up the mode select menu. Then hold R and press this sequence of buttons:
(Hold R) Down, Right, C, Right, Right, L, Start, Left, A, Up, Right, L
You’ll be taken to the secondary level select screen from the 3DO version, the one that lets you choose the Planet X and bonus stages.
The credits code
At the title screen, press Start to bring up the mode select menu. Then hold R and press this sequence of buttons:
(Hold R) C, Left, Up, Right, Left, Right, Down, Down
This brings up the game credits - the full version of them that includes the long sequence praising you for finishing the game, concept art, character sheets, and more.
These credits are normally unlocked by clearing the Planet X stages. If you don’t do that, you just get the staff roll.
Free motion and debug display
There’s a pause menu code in the 3DO version to enable free motion and some other debug features. As far as I can tell, that’s not available on the Saturn version. But you can use Action Replay codes to enable a few things:
1606be76 0003 # Debug messages
1607a08a 0001 # Free movement
The four byte value at at 0606be74 determines the verbosity of the debug messages (0000 0003 is the most verbose).
The four byte value at 0607a088 is normally 0, but if you set it to something else then free movement is enabled. Hold and then use the D-pad to reposition Gex. You can clip through walls and floors, but you’ll take damage from enemies if you touch them.
The 3DO version lets you change other things with the second controller. That functionality seems to be missing from the Saturn version.
Technical details
The function at 06018d08 checks your button presses against a list of codes for the screen you’re on: the mode select screen, the overworld pause screen, and the gameplay pause screen.
The codes are read from bottom to top, and they have “R button being held” interspersed between each button press:
The free movement and debug messages flags are set by the function at 0601750c. This seems to be what parses the command line parameters described on TCRF. The normal arguments are:
gx -real -dram 32000 -nodebug -vramblks 23 -blocks 143 -noprint -music -speechIt’s not totally clear, but I think the Action Replay codes above are undoing the effects of the -nodebug and -noprint switches. Alas, you can’t just edit the string directly; the game crashes.
Outro
You’re welcome and encouraged to use this information and these screenshots on your favorite fan site.
For more coverage of previously-undocumented cheat codes, see:
Are you a fan of other Crystal Dynamics games? If you know Off-World Interceptor Extreme, and want to help me figure something out about it, get in touch.
Check out this blog post from Gregg Tavares, lead programmer for Gex, for the story of its development (thanks to P_Hominid for the pointer)