Indiana Jones and the Infernal Machine

A 100% byte-exact decompilation of LucasArts' Indiana Jones and the Infernal Machine (1999): C source that, built with the same compilers LucasArts used, turns back into the original Indy3D.exe, byte for byte.

This repository is not a port or a modernisation; it is a reference for how the game was actually written, for preservation and to help ports in development.

OpenJones3D was our starting point, but only around 15% of its functions were byte-exact. Partly that was because some of the game wasn't there yet (the INSANE movie player, zlib, the SSE renderer and a few hundred functions that still called into the retail executable), but also because they intentionally fixed bugs and improved things along the way, drifting further from LucasArts' code.

Despite the drift, it still gave us a huge head start: the file names and module layout, function and variable names, structures and types, and readable C for most of the game. That's far more than most decompilations have on day one, and truly awe-inspiring work, the result of nearly a decade spent on this game.

Using AI assistance (mostly Opus 5.5) and tooling loosely based on decomp-toolkit, it took a little over a month to track down the exact compilers used in 1999 and rebuild the code. A byte match on its own proves very little, as code can be bent until the bytes line up, so the goal throughout was the source LucasArts actually wrote, as close as we could get it, not 100% for the sake of it.

Strict rules banned the usual tricks for forcing a match, and every decision the evidence couldn't settle on its own was logged. Of the 3,300 functions, 3,102 rest on evidence alone; the other 198 depend on a measured choice, with me as the final decision-maker. Each one is labelled in the source, and every decision is documented.

In the process, we also released intel-cc-4.0-setup, which installs the Intel C/C++ 4.0 compiler that took some serious sleuthing to find (if anyone has the retail version, please get in touch), and a fix to wibo's heap emulation, both of which should help other decompilation projects. All the files OpenJones3D was missing will also be contributed straight back to it.

A big thank you to smlu of OpenJones3D for their help and support, and to Jack Price-Burns of Decomp Academy, who set up the initial toolchain and the anti-slop guidelines the agents worked under, based on his extensive experience bringing Star Fox Adventures to 100%.

What's in this repository

• The source code for versions 1.2 (latest update) and 1.0 (retail CD), including the functions found only in the debug build.
• The toolchain: a setup script that downloads and verifies every compiler the game was built with, and a build that recreates Indy3D.exe and checks it against your own copy of the game (BUILDING.md).
• The documentation: how it was built, the decisions we made and what we learned about the original code.

Page	What it covers
BYTE-BREAKDOWN.md	Where every byte of the rebuilt executable comes from, and figures for every area and file
BUILDING.md	How to set it up and build it, and which copies of the game work
METHODOLOGY.md	The rules we followed, and what counts as a match
DECISIONS.md	The evidence behind the source, and every kind of choice the evidence couldn't settle
DECISIONS-LIST.md	Every function that rests on one of those choices, and the choice made
SOURCE-TREE.md	How LucasArts laid out their source, how we mirror it, and what else is in the repository
HOUSE-STYLE.md	The coding conventions LucasArts' programmers followed
VERSIONS.md	The releases of Indy3D.exe relevant here (including Steam and GOG), and what 1.2 changed
DEBUG-BUILD.md	The debug build found on the Italian CD, and what it taught us
INSANE.md	The SMUSH/INSANE movie player built into the game
COMPILERS.md	How we identified all five build tools (four compilers and an assembler) and their flags
COMPILER-INTERNALS.md	What we learned about how Visual C++ 5.0 generates code
BUILD-PIPELINE.md	How the build works, step by step, and what it still copies from the retail executable
REPRODUCIBILITY.md	Every download the build depends on, and how each one is pinned

Additional acknowledgments

Thanks to OpenJKDF2, whose work on the related Jedi Knight engine informs many names, and to the authors of wibo, objdiff and the compiler packages listed in REPRODUCIBILITY.md. zlib 1.0.9 is by Jean-loup Gailly and Mark Adler.

License

AGPL v3, inherited from OpenJones3D.