Compatibility tool for Steam Play based on Wine and additional components
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Proton is a tool for use with the Steam client which allows games which are exclusive to Windows to run on Linux and macOS operating systems. It uses Wine to facilitate this.

Most users will prefer to use Proton provided by the Steam client itself. The source code is provided to enable advanced users the ability to alter Proton. For example, some users may wish to use a different version of Wine with a particular title.

Getting Started with Proton from Steam Play

Obtaining Proton from source

NOTE: If you are not comfortable in a command line terminal, or if you find any of the information presented in here strange and uncomfortable, then this is probably not for you. The instructions are likely to be incomplete and require some knowledge and skill on your part, and there is no warranty or guarantee that anyone will help you with this process.

We strongly recommend that most users use the production build of Proton.

The most current source for Proton is here:

Which you can clone to your system with this command:

   git clone proton

After cloning the Proton git repository, the next step will be to obtain the various submodules that go into building Proton:

    cd proton
    #for linux:
    git submodule update --init wine dxvk ffmpeg openal-soft openvr
    #for macos:
    git submodule update --init

If you wish to change any subcomponent, now is the time to do so. For example, if you wish make changes to Wine, you would apply those changes to the wine/ directory.

Building for Linux

To build Proton for Linux, set up a Debian machine with the Steam runtime and chroots as documented in the Steam Runtime repository:

In addition, you will need to install gcc-5 and a long list of dependencies required for Wine. The following set of commands is an example session, and may not be complete.

    cd ~
    git clone
    cd steam-runtime
    #install the end-user steam runtime:
    #install the 32-bit scout_beta runtime:
    ./ --beta --i386
    #enter the 32-bit runtime:
    schroot --chroot steamrt_scout_beta_i386

This will enter the chroot environment, where you would issue the following commands:

    sudo apt-get install gcc-5 g++-5 g++-5-multilib flex bison libosmesa6-dev libpcap-dev libhal-dev libsane-dev libv4l-dev libgphoto2-2-dev libcapi20-dev libgsm1-dev libmpg123-dev libvulkan-dev libxslt1-dev nasm yasm
    sudo update-alternatives --install `which gcc` gcc `which gcc-5` 50
    sudo update-alternatives --set gcc `which gcc-5`
    sudo update-alternatives --install `which g++` g++ `which g++-5` 50
    sudo update-alternatives --set g++ `which g++-5`
    sudo update-alternatives --install `which cpp` cpp-bin `which cpp-5` 50
    sudo update-alternatives --set cpp-bin `which cpp-5`

Next, you need to repeat the process, but for amd64:

    ./ --beta --amd64
    schroot --chroot steamrt_scout_beta_amd64

And then repeat all of the commands to install gcc and Wine dependencies again.

In addition, your host system will need to be able to run Wine in both 64-bit and 32-bit modes in order to create the default prefix. It is recommended to install Wine from your package manager, including its optional dependencies.

The openal-soft build system requires cmake 3.0.2 or later, which is newer than the Steam runtime SDK provides. You will need to build and install a newer cmake into each of the runtimes. For convenience, the script will attempt to use cmake from ~/opt32/bin/ and ~/opt64/bin/, if available.

The following example session obtained and built cmake:

  cd /tmp
  schroot --chroot steamrt_scout_beta_i386
  tar -xzf cmake-3.11.4.tar.gz
  cd cmake-3.11.4
  ./configure --parallel=4 --prefix=~/opt32
  make -j 4 && make install
  rm -rf cmake-3.11.4
  schroot --chroot steamrt_scout_beta_amd64
  tar -xzf cmake-3.11.4.tar.gz
  cd cmake-3.11.4
  ./configure --parallel=4 --prefix=~/opt64
  make -j 4 && make install

Finally, change your directory back to proton, and run:

    cd ../proton

That should configure and build Wine, and then package the result up into dist/. It is important to examine the output near the end of build/{64,32}/config.log to ensure that you have all of the relevant libraries in each chroot. Search for 'executing Makefile commands' in config.log to find messages about missing libraries. It is normal to be missing a few libraries, including OpenCL, OSS, and libav.

NOTE: The script builds most components inside the Steam runtime chroot. However, dxvk will not build in that environment, so the script will build it on your local system. This will require you to be able to build dxvk on your local system; refer to the dxvk for more details.

Building for macOS

To build Proton for macOS, install the latest Xcode command line tools, as well as cmake (for openal-soft), a recent nasm (for libjpeg-turbo), libtool, and automake. You can use a packager like Homebrew to find these packages.

    brew install cmake nasm libtool automake

Then run:


TODO - Surely there are other dependencies we have not listed there.

It is important to examine the output near the end of build/{64,32}/config.log to ensure that you have all of the relevant libraries required to build Wine properly.


Once built, the dist/ directory will contain the files which can be distributed through Steam. For testing purposes, you should be able to clear out the files in your steamapps/common/Proton directory and replace them with the contents of dist/. The proton script will unpack the files on first run. Note that if you use the Steam client to verify local files, it will restore the production version of Proton.

Each component of this software is used under the terms of their licenses. See the LICENSE files here, as well as the LICENSE, COPYING, etc files in each submodule and directory for details.

Runtime Config Options

Proton can be tuned at runtime to help certain games run. The Steam client sets some options for known games using the STEAM_COMPAT_CONFIG variable. You can override these options using the environment variables described below. The best way to set these environment overrides for all games is by renaming to and modifying it appropriately. If you want to change the runtime configuration for a specific game, you can use the Set Launch Options setting in the game's Properties dialog in the Steam client. You can launch the game as you would with "PROTON_VARIABLE=1 %command%" (source).

To enable an option, set the variable to a non-0 value. To disable an option, set the variable to 0. To use Steam's default configuration, do not specify the variable at all.

All of the below are runtime options. They do not effect permanent changes to the Wine prefix. Removing the option will revert to the previous behavior.

Compat config string Environment Variable Description
PROTON_LOG Convenience method for dumping a useful debug log to $HOME/steam-$APPID.log. For more thorough logging, use
PROTON_DUMP_DEBUG_COMMANDS When running a game, Proton will write some useful debug scripts for that game into $PROTON_DEBUG_DIR/proton_$USER/.
PROTON_DEBUG_DIR Root directory for the Proton debug scripts, /tmp by default.
wined3d11 PROTON_USE_WINED3D11 Use OpenGL-based wined3d instead of Vulkan-based DXVK for d3d11.
nod3d11 PROTON_NO_D3D11 Disable d3d11.dll, for games which can fall back to and run better with d3d9.
noesync PROTON_NO_ESYNC Do not use eventfd-based in-process synchronization primitives.