KisakCOD – open-source reimplementation of Call of Duty 4 Multiplayer

KisakCOD is an open-source, fully buildable reimplementation of Call of Duty 4 Multiplayer’s .exe. It targets mod developers and COD4 enthusiasts and has appeared on the Hacker News front page. The project ships a development blog at https://lwss.github.io/Duty-Of-Kisak/ and states that Call of Duty 4 is roughly a 20-year-old game with known exploits that maintainers intend to address as they learn about them.

Building it is a full native Windows toolchain path, not a packaged drop-in binary. Requirements are Windows, Visual Studio 2022, CMake 3.16 or newer, the DirectX SDK 2010, and a Steam copy of Call of Duty 4. After cloning, generate-project.bat produces Visual Studio solutions under build-sp, build-mp, and build-dedi. The build does not stand alone: you must copy the full COD4 game files into bin/(BUILD_TYPE)/ (including small assets such as localization.txt), plus deps/binklib/binkw32.dll, all of deps/msslib/dlls/*, and deps/steamsdk/steam_api.dll, then run from Visual Studio or the resulting .exe.

For engineers and modders, a rebuildable multiplayer executable changes the surface area for inspection and extension. Instead of treating the commercial .exe as a black box, developers get project files for single-player, multiplayer, and dedicated-server targets and can iterate in a modern Visual Studio 2022 workflow. That matters for people who want client or server changes, tooling, or research on an engine that otherwise only exists as a closed binary tied to Steam assets and third-party libraries (Bink, Miles Sound System, Steam API).

In market terms this sits beside the still-sold COD4 install, not as a free replacement game. You still need a legitimate Steam copy and must supply proprietary runtime pieces the open repo does not replace. The value is control of the multiplayer executable layer—source-level access for mods and enthusiasts—while game data, codecs, audio DLLs, and Steam integration remain external dependencies. Relative to typical reverse-engineering or binary patching of old multiplayer titles, a CMake-driven, fully buildable reimplementation lowers the barrier to systematic changes and shared fixes.

Practical next steps: confirm you meet the toolchain and Steam ownership requirements before cloning; expect a full game-file copy into the build output, not a cherry-picked subset; and treat multiplayer exposure carefully given the project’s own note about known exploits on a ~20-year-old title. Watch the Duty-Of-Kisak development blog for build and security updates, and track whether exploit fixes land as maintainers become aware of them.