There’s a preview of Disruptor on the PlayStation Picks sampler disc from 1996. Disruptor was the first game from Insomniac Games, the studio that later became famous for the Spyro the Dragon and Ratchet & Clank games.
The file timestamps on the sampler disc are from 1996-09-17, a month earlier than the ones on the final U.S. version (1996-10-16). I found some interesting things lurking in the data:
Normally you can play three missions and watch auto demos of three more. The additional ones can be made playable, but they’re unfinished.
The demo build prevents you from accessing the pause menu. But behind the restrictions are cheat codes that differ from the final version.
You can get a patch that enables the three extra missions and the hidden cheats from GitHub. Details are below!
Playing more missions
The demo normally lets you play the Rooftops, Antarctica, or Io Sulfur Mines missions. It also gives you the option to watch auto demos of three more missions.
The function that handles input on this screen lives at 800219f4. It’s got some logic that looks like this pseudo-Python (adapted from Ghidra’s decompilation):
if pressed_button & 0x08f0 != 0:
if preview_cursor_8005ee54 < 3:
advance_screens_8005f090 = 1
if preview_cursor_8005ee54 == 0:
mission_index_8005ed24 = 6
elif preview_cursor_8005ee54 == 1:
mission_index_8005ed24 = 10
elif preview_cursor_8005ee54 == 2:
mission_index_8005ed24 = 13
mission_id_8005eecc = mission_table_800558f0[mission_index_8005ed24]
auto_demo_status_8005f09c = 3That is, if you press Start (or any of the face buttons), the function looks at the position of the cursor on the menu. It maps that value to a mission ID (using a two-step mapping, strangely), and then updates the variable I’m calling auto_demo_status_8005f09c to 0x03.
Nullifying that last update is enough to make the three extra missions playable. You can run around the first part of Mars Desert, but it freezes if you try to go past this part:
The auto demo strategically cuts off before this point, of course – presumably because the developers knew things weren’t finished.
The Orbiting Habitat mission doesn’t crash – the first two sections work well. But there doesn’t seem to be a way to progress to the end.
The Fortress mission also crashes after the part the auto demo shows, alas.
Cheat controls
There is some interesting logic in the function that handles input on the pause screens (which lives at 8003ae70):
if pause_mode_8005ee28 == 4:
# ...
if (
((held_button_80064e28 & 0xc) == 0x0c) and
((held_button_80064e2c & 0xc) != 0x0c)
):
invincibility_80064df1 = 1 - invincibility_80064df1That is, if you’re on the pause screen with ID 4, pressing L1+R1 enables invincibility:
The hex pattern for L1 is
0x08. This is OR-ed with the hex pattern for R1, which is0x04. The result is0x0c.The code compares the current frame’s input against the previous frame’s. If a button’s bit is set in the first address but not in the second, it’s considered a fresh “press” rather than a “hold.”
But how do we get to pause screen 4? There’s no way to do it from within the demo:
Pressing Start opens the Map screen, which is ID
1.Pressing Select ends the demo.
The logic for the Select handling looks like this:
if held_button == 0x0100:
switch_screens_8005f090 = 1
end_demo_8005ef50 = 1I nullified the instructions that implement that logic and made Select update the pause screen ID instead.
Now pressing Select makes the screen dim:
Pressing L1+R1 now enables invincibility, as foretold by the code.
Furthermore, pressing L2+R2 gives you full health, full ammo, and full Psionic power:
The final version of the game uses more complicated button sequences to enable these cheat effects.
If you press Up and Down on the dimmed screen, you’ll hear the usual menu navigation sound effects. That’s because it’s really the Paused screen that’s in the final version.
You can’t see the menu cursor, but you can Resume Mission, Abort Mission, and adjust Sound Volume and Music Volume if you’re aware of what invisible selection you’re making.
Outro
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There are more articles about modifying pre-release demo discs in the archive.
