Extending the demo: Vs. (PlayStation)
Exciting alternative music
In this edition:
There’s a preview of Vs, the 1997 PlayStation fighting game, on one of the Official PlayStation Magazine demo discs.
The demo restricts what you can play, but it’s based on a more-or-less complete build of the game. I made a patch to lift its limits.
The demo predates the final version by more than 2 months, and has some noticeable differences.
Get the patch from GitHub. Details are below…
Build differences
Without any hacking, you’ll notice some differences between the demo build and the final version. For example, the demo’s title screen apologizes for its lack of music:
Due to the size constraints of this demo, the exciting alternative music in this game cannot be included
The final game has these tracks in its sound test:
Power (Razed In Black)
Hard Life (Los Infernos)
S.O.S. (The Suicide Machines)
No Face (The Suicide Machines)
Pursuit (Razed In Black)
Future Unknown (Razed In Black)
Cyberium (Razed In Black)
Misunderstood (Los Infernos)
You can’t see it without hacking, but the demo build has an extra track: Never.
Its file is missing, so you can’t listen to it for identification purposes. But this 1997 press release suggests that it’s from the band Pigs in Space. This YouTube video, uploaded by one of the band members, provides confirmation. Its description says:
This song is why we can claim to have been a “Professional” band. Never was featured on the PS1 fighting game Vs. released by THQ in 1997.
There are lots of other small differences between the demo build and the final version. For example, the demo’s main menu has an Option item, but this is on the title screen in final version:
Several characters have different heights listed. For example, Paco is 6 ft. 2 in. in the demo, but 5 ft. 7 in. in the final version:
Some menu labels don’t match between the version. The demo uses Start / Cancel / Option before a fight starts. The final uses OK / Cancel / Config:
During gameplay, you can see that the Defensive Fire Indicator is missing in the demo. According to the manual, this:
Indicates the amount of defensive fire possessed by each fighter. A full indicator increases a fighter’s ability to block and counter throw moves, and vice-versa.
Vs. is based on a Japanese game called Fighters’ Impact. It doesn’t have this meter, so it may not have been implemented in time for the demo build.
EGM’s top review complained about the difficulty level in the final version:
…the computer must have a red belt in butt whuppin’. Your paltry orange belt won’t cut it here, so you’ll be relegated to playing with friends to gain much enjoyment. Like most games with incredibly high difficulty - even on Easy settings —you will degenerate into lifeless patterns of block, counter, dodge, counter, Sweep, counter.
The CPU in the demo version seems to be much weaker, however. It sometimes gets a character stuck doing a single move, and won’t move on until you land a hit:
Based on the file timestamps, the demo is from 1997-08-06. The final version is from 1997-10-28, almost 12 weeks later.
Technical details
Amazingly, a single flag determines whether demo restrictions should be applied. If the 16-bit value at 80133ea6 is set to 1, the game limits which modes, characters, and stages you can play.
The first read of that value is by these instructions:
800faf9c lui v1,0x8013
800fafa0 lh v1,0x3ea6(v1)The first one prepares the first four bytes of the address (0x8013). The second one completes the address and loads the target value into register v1.
I changed this read into a write:
800faf9c lui v1,0x8013
800fafa0 sh r0,0x3ea6(v1)Register r0 always contains a value of 0, so this prevents restrictions from being applied.
Later in the startup process, the demo flag gets written again:
8001ad14 ori v0,r0,0x1
...
8001ad50 lui at,0x8013
8001ad54 sh v0,0x3ea6(at)I replaced the final instruction with a nop command, which keeps the write from happening.
This is enough to make all of the modes and characters available.
Although it looks like the extra stages are still unavailable (they keep their 🚫icon), they actually do work:
I’ve encountered another game with demo restrictions implemented like this: Digital Pinball: Necronomicon for Saturn. A single flag turns the preview version into the release version!
Outro
For many more articles on prototype builds hiding out on demo discs, see my archive here on Substack. I’ll be back with more soon!
