Proton is a tool for use with the Steam client which allows games which are exclusive to Windows to run on the Linux operating system. 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.

New in Proton 4.11-7:
- Major improvements to controller hotplugging. For games which support it, controllers should now work even if plugged in after the game has started.
- Improve controller support for games that use the Rewired Unity library, like ICEY.
- Upgrade wine-mono to 4.9.3, which improves font rendering and some minor game compatibility problems for games such as Age of Wonders: Planetfall.
- Fix crash launching Kingdom Come: Deliverance.
- Upgrade DXVK to v1.4.2.
- Upgrade D9VK to 0.22.
- Fix possible crash with some VR games.

New in Proton 4.11-6:
- The Surge 2 is now playable (currently doesn't work on radv).
- Beginnings of support for Rockstar's new launcher. There is more work to do here, but Grand Theft Auto 5 should be playable again.
- Update DXVK to v1.4.