What is this?
IW4L is a Call of Duty runtime written from scratch in Rust on Bevy and wgpu. You point it at an existing Modern Warfare 2 install you already own, and it loads that game's data into its own independent engine using reverse-engineered on-disk layouts.
IW4L is a Call of Duty runtime written from scratch in Rust on Bevy and wgpu. You point it at an existing Modern Warfare 2 install you already own, and it loads that game's data into its own independent engine using reverse-engineered on-disk layouts.Is this a mod for the retail game or a brand-new engine?It's a from-scratch engine/runtime, not a patch applied to the original binaries. It reads MW2's asset files but reimplements rendering, simulation and networking independently; retail protocols, the original ABI and patched executables are explicitly out of scope.
It's a from-scratch engine/runtime, not a patch applied to the original binaries. It reads MW2's asset files but reimplements rendering, simulation and networking independently; retail protocols, the original ABI and patched executables are explicitly out of scope.How do I build and run it?Install the OS packages listed in docs/BUILD.md (compiler, ALSA, udev, X11/Wayland headers on Linux; Xcode command line tools on macOS), then build with the profile.play development profile for day-to-day runs, or PROFILE=release for the release binary. docs/WINDOWS.md covers the portable Windows build.
Install the OS packages listed in docs/BUILD.md (compiler, ALSA, udev, X11/Wayland headers on Linux; Xcode command line tools on macOS), then build with the profile.play development profile for day-to-day runs, or PROFILE=release for the release binary. docs/WINDOWS.md covers the portable Windows build.Do I need to already own Modern Warfare 2 to use it?Yes — point the IW4LGAMES variable at the folder with your existing MW2 (or MW3/Black Ops) install. No game assets ship with IW4L itself, and it only reads those files without ever writing back to them.
Yes — point the IW4LGAMES variable at the folder with your existing MW2 (or MW3/Black Ops) install. No game assets ship with IW4L itself, and it only reads those files without ever writing back to them.Is this stable enough for regular play?No — there are no releases yet, and the API, config format, caches and wire protocol all change between commits, so everyone must be on the same build. The netcode has only been used for arranged playtests among people who agreed in advance, not for public lobbies.
No — there are no releases yet, and the API, config format, caches and wire protocol all change between commits, so everyone must be on the same build. The netcode has only been used for arranged playtests among people who agreed in advance, not for public lobbies.What platforms does it run on?Linux, macOS (via Metal through wgpu), and a portable Windows build.
Linux, macOS (via Metal through wgpu), and a portable Windows build.Does it send any data over the network on its own?No — IW4L sends nothing home. Diagnostic files and caches stay on your disk until you choose to attach them to a bug report.
No — IW4L sends nothing home. Diagnostic files and caches stay on your disk until you choose to attach them to a bug report.How does the multiplayer networking work?IW4L uses a custom peer-to-peer UDP wire protocol with its own delta compression, reliability and reconciliation. A QUIC-based master server only helps peers find each other and does not relay game traffic.
IW4L uses a custom peer-to-peer UDP wire protocol with its own delta compression, reliability and reconciliation. A QUIC-based master server only helps peers find each other and does not relay game traffic.How are the original game's shaders handled without DirectX?Retail D3D9 Shader Model 3 shader tokens are translated ahead of time into WGSL, so the runtime never needs DirectX to render.
Retail D3D9 Shader Model 3 shader tokens are translated ahead of time into WGSL, so the runtime never needs DirectX to render.Who actually wrote this project?The entire codebase was written by an LLM, built from reverse engineering the original binaries with Ghidra and cross-referencing public projects like OpenAssetTools, IW4x and KisakCOD.
The entire codebase was written by an LLM, built from reverse engineering the original binaries with Ghidra and cross-referencing public projects like OpenAssetTools, IW4x and KisakCOD.Which games' assets can it load?MW2 zones are read natively, while MW3 and Black Ops assets are converted into the same internal assetiw4 intermediate representation.
MW2 zones are read natively, while MW3 and Black Ops assets are converted into the same internal assetiw4 intermediate representation.Which topics is it in?shader, udp, physics, webgpu, multiplayer, game-modding, protocol, game-engine, gamedev, p2p, simulation, rendering
shader, udp, physics, webgpu, multiplayer, game-modding, protocol, game-engine, gamedev, p2p, simulation, rendering