Fallout 1 & 2 reversing and modding resource

Updated 2026-05-09

You can find additional information and code at github.com/rotators

Fallout2.exe

Structures

Sfall references

Fallout 2 RE references

Function and variable offsets

Call structure

x64dbg database

Fallout_1_and_2_IDA68.rar - IDA database

f2_res.dll (High resolution patch)

Symbols

Modding

Comprehensive Fallout 2 Modding Guide - source

Quantum's Fallout Modding 'How To' Videos

File formats

FormatTools
AI.TXT - Description of combat parameters for the player and all NPC classes in the gameFallout 2 - Proto Manager
PARTY.TXT - Party-member registry, combat-control option whitelist, and companion level-up data.Text editor
Pip-Boy text data - quests.txt, holodisk.txt, quest status, holodisk text, and GVAR-controlled display rules.Text editor
ACM - Interplay compressed audio for music, speech, and sound effects.Use libacm, acm2wav or Game Audio Player for playback.
AAF - The AAF Font File Format is used to store fonts.Fallout Service Box: Font Editor
BIO - Story for premade characters (GCD).Text editor
CFG/INI - Runtime configuration files, parser behavior, sfall INI settings, high-resolution options, and movie sidecars.Text editor
Critical hit tables - Executable combat tables, sfall/CE override INI layout, damage flags, and combat message dependencies.Text editor, hex editor
DAT - Archive containers for Fallout 1/2 resources, including DAT1 and DAT2 layouts.Dat Explorer 1.43, many others
Elevators.ini - sfall/CE elevator destination tables, interface templates, and script activation rules.Text editor
FON - Fonts used for text on the world mapFON editor
FRM - Indexed art, animation frames, rotations, offsets, FID lookup, and palette-dependent rendering.Titanium FRM browser, Graphics viewer 1.36 and many others.
INT - Compiled script bytecode for Fallout and Fallout 2 SSL scripts.use int2ssl.exe included in sfall modderspack to decompile or source repo.
SSL - Source language and build format for Fallout and Fallout 2 scripts.sfall SSLC, Fallout 2 script library
SCRIPTS.LST - Indexed registry for compiled INT scripts, dialogue MSG binding, and script local-variable metadata.Text editor
Savegame structure - SAVE.DAT, saved map sidecars, party PRO sidecars, automap data, and sfall save extensions.Hex editor, gzip tools
GCD File Format - Premade characters.CGCD
GAM - GAM files are indexed text files. They contain global variables for each core Fallout game and its mapsText editor
LIP - Talking-head lip-sync timing for speech audio.LIP editor, wav2lip
LST - Line-indexed tables, art FID resolution, critter/head metadata, and filename construction.Text editor
MAP - Maps used for locations.Patched BIS mapper
MSG - Text message lists for dialogue, object names, UI strings, map names, and combat text.Text editor
MSK - World-map walk masks that mark blocked terrain pixels.MSK tools, msk2bmp
PAL/COL - Fallout palette files, RGB555 lookup, color tables, and animated palette ranges.Fallout default color sheet
PRO - Prototype, every item, critter, wall, tile, and piece of scenery has its own corresponding PRO file.Fallout 2 - Proto Manager
RIX - ColoRIX indexed bitmap format used for startup/loading splash screens.Graphics viewer 1.36 to load/save
MVE - Interplay movie container for intro, ending, logo, credits, and cutscene videos.Various
SVE - Frame-numbered subtitle cue lists for MVE movies.Text editor
Worldmap.dat - Serialized world-map state and related world map definition files.Fallout2 worldmap.txt interactive browser and parser
World-map text config - maps.txt, city.txt, and worldmap.txt editable world-map definitions.Text editor, Fallout2 worldmap.txt interactive browser and parser

Artwork

The Complete Fallout 1 & 2 Artwork

Animation

Animation names

Animation viewer - TypeScript source

Scripting

Fallout 2 opcodes - does not include sfall opcodes. Official Fallout 2 scripts source code

Worldmap

Fallout2 worldmap.txt interactive browser and parser

Watcom

Watcom is the compiler that was used to compile both Fallout 1 and 2.

Watcom does not support the __fastcall keyword except to alias it to null. The register calling convention may be selected by command line switch. (However, IDA uses __fastcall anyway for uniformity.)

Up to 4 registers are assigned to arguments in the order eax, edx, ebx, ecx. Arguments are assigned to registers from left to right.

If any argument cannot be assigned to a register (say it is too large) it, and all subsequent arguments, are assigned to the stack. Arguments assigned to the stack are pushed from right to left. Names are mangled by adding a suffixed underscore.

eax->func(edx, ebx, ecx, push...)

func(eax, edx, ebx, ecx, push...)

Read more

ASM

x86 reference

x86 and amd64 instruction reference

x86 opcode table

Online x86 / x64 Assembler and Disassembler

Reversing tools

OllyDBG - debugger

x64dbg - debugger

IDA 7 freeware - disassembler/debugger

IDA 5 - Old version of IDA, suitable for DOS reversing

PE explorer

HxD - Freeware Hex Editor and Disk Editor ( alternatives)

DLL Export Viewer v1.66

Scylla - Imports viewer

idbutil - Tool for dumping data from IDA pro databases

Additional stuff

IDA database

Fallout_1_and_2_IDA68.rar

idbtool.exe

idbtool.exe --enums Fallout2.idb > enums.txt

idbtool.exe --names Fallout2.idb > names.txt

Fallout tools

List of tools

Fallout 2 @ NMA

Team-X Utilities

ToolAuthorDescription
Sfall Script EditorSfall teamAllows to edit and compile SSL scripts in a convenient way.
Dat Explorer 1.43DimsDAT file packer / unpacker. With a graphical interface.

Sfall

A set of engine modifications that greatly enhances the engine. Includes fixes for bugs in the original engine, allows fallout to run correctly on modern operating systems, and adds additional features for modders.

Binary distros

Sourceforge

Source code

Check out the code from the main repo.

DirectX

Main SDK needed is DirectX june 2010. dinput.lib from DirectX august 2007 also needed.

Mirror: DirectX SDK Collection

sfall dev

Projects

ProjectDescription
Fallout 1 Reference EditionFallout 1 RE project by Alexander Batalov.
Fallout 1 Community EditionFallout Community Edition is a fully working re-implementation of Fallout, with the same original gameplay, engine bugfixes, and some quality of life improvements, that works (mostly) hassle-free on multiple platforms.
Fallout 2 Reference EditionFallout 2 RE project by Alexander Batalov. Announcement post
Fallout 2 Community EditionFallout 2 Community Edition is a fully working re-implementation of Fallout 2, with the same original gameplay, engine bugfixes, and some quality of life improvements, that works (mostly) hassle-free on multiple platforms.
Fallout 2 Javascript portInactive engine implementation
DarkFO, a post-nuclear RPG remake (of Fallout 2)Inactive engine implementation in TypeScript and Python
falltergeistOpensource crossplatform Fallout 2 game engine written in C++ and SDL.
Fallout 2 tweaksA collection of convenience tweaks, common sense changes, and cheats for Fallout 2. It is highly configurable, any component can be used with or without others. Some components also allow fine tuning.
Fallout 2 map editorFallout 2 map editor by Jan Simek
KlamathC++ utilities for working with Fallout 1/2 assets
Fallout et Tu (Fallout 1 in 2)A project that aims to bring Fallout 1 into the Fallout 2 engine.

Misc

Buy

GameStores
FalloutGOG, SteamDB, Epic
Fallout 2GOG, SteamDB, Epic