OpenMM2

OpenMM2 is an open source reimplementation of Midtown Madness 2 (Angel Studios / Microsoft, 2000) for modern Linux and Windows systems.

The main goal is preservation: the original game's mechanics (vehicle handling, AI, game modes and rules) should behave as they did in 2000. On top of that, OpenMM2 adds:

• any resolution and aspect ratio, windowed or fullscreen, HiDPI aware
• a Vulkan renderer with an automatic OpenGL fallback
• online multiplayer over UDP with automatic port forwarding (UPnP)
• a Windows installer, and native Linux builds

Status: early but playable. London and San Francisco, cruise, Blitz, checkpoint and circuit races, the crash courses, Cops and Robbers and online multiplayer all run from the original game data. Behaviour is checked against the original game function by function; the results, and the gaps still open (mostly in network play), are in docs/parity/.

You need the original game

OpenMM2 contains no Midtown Madness 2 content: no models, textures, sounds, music or text. It loads them from your own copy of the game, which can be any of:

• the original CD in a drive (or a copy of its contents)
• a disc image: .iso, .bin/.cue, .img (2048- and 2352-byte sectors)
• an existing Midtown Madness 2 installation folder (the one containing MM2CORE.AR)

OpenMM2 never runs, modifies or bypasses the copy protection of the original executable, and it does not need a CD key. Optionally the game archives (about 400 MB) are copied to the hard disk once, so the disc or image is not needed afterwards.

This project is not affiliated with or endorsed by Microsoft, Rockstar Games or Angel Studios. "Midtown Madness" is a trademark of its respective owner.

Installing

Windows

Run OpenMM2-<version>-windows-x86_64-setup.exe (64-bit Windows 7 or later). The installer asks where your Midtown Madness 2 files are and checks them before continuing. You can also skip that step; OpenMM2 asks on first start.

To update, run the new version's installer. It finds the installed version and updates it in its folder, keeping your settings, driver profiles, replays and game data; the game data and shortcut choices are filled in from last time, so an update is Next, Next, Install. Files that the new version no longer ships are removed. Running the same version again repairs the installation, and an older version asks before it replaces a newer one. Close OpenMM2 first: setup waits (Retry/Cancel) until it is closed.

Silent installs accept:

Option	Meaning
/S	silent install
/D=C:\Games\OpenMM2	install directory (must be last, unquoted)
/SOURCE=<path>	game data: disc image, drive root such as D:\, or install folder
/COPYDATA	copy the game archives to <install dir>\gamedata
/ALLOWDOWNGRADE	replace a newer installed version (refused otherwise)

Exit code	Meaning
0	success
1	cancelled or failed (for example, another program held a file open)
2	installed, but the /SOURCE game data was rejected (OpenMM2 asks on first start)
3	nothing changed: a newer version is installed and /ALLOWDOWNGRADE was not given
4	nothing changed: OpenMM2 is running

The uninstaller also stops while OpenMM2 is running (exit code 4 when run as uninstall.exe /S _?=<install dir>; otherwise it restarts itself from a temporary copy and returns at once).

A silent update keeps the last installation's choices: game data, shortcuts and developer tools. /D= naming another folder moves the installation: setup removes the old folder's program files and uninstaller but keeps its gamedata folder and openmm2-install.ini (and keeps using that game data unless /SOURCE is given), so the old folder stays only if it holds them. The installer lists what it installed in install-manifest.txt, which the next update and the uninstaller use to remove exactly those files.

The portable ZIP (OpenMM2-<version>-windows-x86_64-portable.zip) needs no installation: unpack it anywhere. Because it contains portable.txt, settings are kept in a user folder next to openmm2.exe.

Linux

Unpack OpenMM2-<version>-linux-x86_64.tar.gz and run bin/openmm2, or build from source (below). cmake --install puts a desktop entry, AppStream metadata and icons in the usual places.

Pointing OpenMM2 at the game

On first start OpenMM2 shows a setup screen for choosing the game data (run openmm2 --setup to show it again). It can also be done from a terminal:

openmm2 --check-source ~/Downloads/midtown2.iso           # is this usable?
openmm2 --import-source /run/media/$USER/MIDTOWN2          # copy archives to the user data folder
openmm2 --source /path/to/midtown2.iso                     # use for this run only

Settings live in openmm2.ini:

Platform	Settings	Data (imported game files, saves, logs)
Linux	$XDG_CONFIG_HOME/openmm2 (~/.config/openmm2)	$XDG_DATA_HOME/openmm2 (~/.local/share/openmm2)
Windows	%APPDATA%\OpenMM2	%LOCALAPPDATA%\OpenMM2
Portable	user\ next to the executable	user\ next to the executable

The Windows installer records its choice in openmm2-install.ini next to openmm2.exe; per-user settings take precedence over it.

Building from source

Requirements:

• CMake 3.25 or newer and Ninja
• a C++23 compiler: GCC 14+, Clang 18+ (with libstdc++ 14+ or libc++ 18+), or Visual Studio 2022 17.10+
• glslc (shaderc) or glslangValidator (glslang) for the Vulkan shaders
• Git (dependencies are fetched at configure time)

Other dependencies (SDL3, miniz, ENet, miniupnpc, Dear ImGui, Vulkan headers, volk, VMA, GoogleTest) are downloaded and built automatically at pinned versions. On Linux, installed SDL3 and GoogleTest packages are used when available (-DOPENMM2_USE_SYSTEM_DEPS=OFF to always build them).

Linux

# Arch Linux
sudo pacman -S --needed base-devel cmake ninja git shaderc glslang sdl3 gtest
# Fedora
sudo dnf install cmake ninja-build gcc-c++ git glslc glslang SDL3-devel gtest-devel
# Debian/Ubuntu (25.04 or newer for a recent enough compiler and SDL3)
sudo apt install build-essential cmake ninja-build git glslc glslang-tools libsdl3-dev libgtest-dev

cmake --preset linux-gcc-release          # or linux-clang-release, *-debug
cmake --build --preset linux-gcc-release
ctest --preset linux-gcc-release

Binaries end up in out/build/<preset>/bin. Without presets, the usual cmake -S . -B build -G Ninja && cmake --build build works as well.

Windows (MSVC)

Install Visual Studio 2022 with the "Desktop development with C++" workload and the Vulkan SDK (for glslc). From a "x64 Native Tools Command Prompt":

cmake --preset windows-msvc
cmake --build --preset windows-msvc-release
ctest --preset windows-msvc-release

Visual Studio can also open the folder directly and use the same presets; windows-vs2022 generates a .sln instead.

Cross-compiling for Windows (MinGW-w64)

sudo pacman -S mingw-w64-gcc        # Debian/Ubuntu: mingw-w64 (GCC 14+ needed)
cmake --preset mingw-cross-release
cmake --build --preset mingw-cross-release

If Wine is installed, ctest --preset mingw-cross-release runs the tests through it.

Tests with the original game data

Tests that need the retail files are skipped unless OPENMM2_GAME_DATA points at a disc image, disc or installation:

OPENMM2_GAME_DATA=~/Downloads/midtown2.iso ctest --preset linux-gcc-release

Packages

cpack --preset linux-release                              # .tar.gz (Linux)
cpack --preset windows-portable                           # portable .zip (MSVC)
cmake --build --preset windows-msvc-release --target package_installer   # setup .exe

The installer is built from packaging/windows/openmm2.nsi and needs NSIS 3 (makensis); CMake finds it in Program Files\NSIS or on PATH. A native makensis also works when cross-compiling. The icon artwork is in packaging/icons (render-icons.sh regenerates the bitmaps from the SVG).

packaging/windows/test-installer.sh <build dir> tests the installer under Wine: new installations, updates (also from the last release's installer), repair, downgrades, a running game, a failed game data copy, moving with /D=, uninstalling, and the wizard's pages. It uses synthetic game data, so it needs no game files. It needs Wine, a MinGW-w64 C compiler and makensis (MAKENSIS=<path>, or MAKENSIS_WINE=1 with the Windows makensis.exe); the script's header lists its options. CI runs it on the MinGW build.

packaging/windows/test-installer.sh out/build/mingw-cross-release

mm2tool

mm2tool is a developer tool for looking inside the game data:

mm2tool source                                   # list detected game sources
mm2tool ls midtown2.iso 'tune/*.vehcarsim'       # all archives mounted as the game sees them
mm2tool cat midtown2.iso tune/vehicle/vpbug.vehcarsim
mm2tool extract midtown2.iso local/extracted 'city/*'

Run mm2tool without arguments for the full list of commands. Keep anything you extract out of the repository (the local/ folder is ignored by Git).

Contributing

See CLAUDE.md for the project rules and code layout, and docs/ for architecture notes and file format documentation. In short: no game data in the repository, no circumvention of the original game's copy protection, and behaviour that is inferred rather than known is marked as such.

License

OpenMM2 is free software, released under the GNU General Public License, version 3 or later (see LICENSE). Binary packages include the licences of the bundled third-party libraries in licenses/.