Modifying (JC1)

This article describes modifying Just Cause (1).

For other modifying info and relevant warnings see the Modifying main article. Proceed at your own risk.

Introduction[]

It is disappointing that Eidos has not included any SDK for its community. However, there have been ways to extract their archives. This article documents as much JC-related modding as possible.

Due to encryptions, difficult coding and few interest from the relevant community, there were very few and small successful attempts at modifying this game until the 2020s when several major breakthroughs were made and work continues to this day.

Extracting (old)[]

Thanks to the MultiEx community and QuickBMS, extracting the *.ARC files has been made possible.

First, locate the folder containing your game Archives. (Its named should be named Archives, for obvious reasons.) Create a new text (.txt) file in that folder, then paste the following code in it:

for i = 1 < 0xFFFF
get NSIZE long
getdstring name nsize
get offset long
get size long
if NSIZE == 0
cleanexit
endif
log name offset size
next i

Save the file.

Now download QuickBMS, and extract it to your Desktop. You may delete the src folder if you want. Double click on quickbms.exe, then for the first part, select the text file you created. For the next part, select one of the archives, from pc1.arc to pc4.arc. Then create another folder to save the extracted content to. Hit "OK", then once it is finished, you have now extracted the content from the game!

Extracting (new)[]

A newer and more capable file extracting tool is the JC.ARC.Tool.

File types[]

*.ARC[]

This is an Archive. QuickBMS, along with the script included above, are able to open most of them. (Note that pc0.arc cannot be opened with the above script.)

As a reference, these are the first 4 bytes (headers) in the 5 archive files normally included with Just Cause:

File Name	Header
pc0.arc	4C 00 00 00
pc1.arc	04 00 00 00
pc2.arc	04 00 00 00
pc3.arc	04 00 00 00
pc4.arc	04 00 00 00

In fact, pc0 is most likely unopenable due to its unusual header. That, or the header could be indicating a different file format, with which will need a new script.

*.DDS[]

Stands for Direct Draw Surface. These files are used with DirectX to apply textures to models. Paint.NET has a plugin if you are looking to convert these to a normal format.

Main article: DirectDraw Surface.

*.BFSM[]

Still an unknown acronym, these files appear to control how NPCs function. Acronym may stand for "Binary Finite-State Machine" as FSM's are quite common with NPC programming.

*.LOD[]

Normally standing for Level Of Detail, these files could be the actual models, containing actual point-by-point info, as well as animations.

Main article: Level Of Detail.

List of all known JC1 mods[]

Two trainers can be downloaded here.
See Myths for the unfinished superman mod that doesn't seem to exist anymore.
This link leads to a Cheat Engine script which allows to spawn any vehicle with any faction colors and symbols, as well as repaint already existing ones. The video in the end of the page explains how to use it properly.
It's rumored that there's a mod that changes the games resolution to make it 16:9 and increase the resolution. The game itself is only 4:3.
- Running the game on some laptops with Windows XP is known to also automatically stretch the game to fit the screen, tho results may differ.
Just Cause Multiplayer.
It's rumored that a "Just Cause Unlimited" major overhaul mod is being worked on.
Multiple beta vehicles found in the game files have been restored to functionality, but these are not currently available as released mods. See Cut game content from Just Cause for a full list of such vehicles.