Only the Linux version includes Proton.
Optionally you can opt-in the beta program for faster access to new features.
Announced on August 21st, 2018 as a rework of Steam Play, Proton is included in the Steam Linux client by default and Valve whitelists 100+ games known to work out-of-the-box. However, by changing a switch in Steam's settings, Proton can be enabled for all Windows games even if they don't currently work.[N 1] Users began compiling test results into compatibility lists, and there is now a portal for checking which games work, linked below. As of the January 17th, 2019 Steam Client beta, Proton can be force-enabled in per-title properties, including for running the Windows version of games with a Linux port.
Proton is based on Wine and includes additional components like DXVK (a library that translates Direct3D 9, 10 and 11 calls to Vulkan on-the-fly), vkd3d-proton (a library that translates Direct3D 12 to Vulkan) and FAudio (an XAudio reimplementation). As a Steam Play feature, it avoids having to set up an additional Steam installation for Wine, which used to be the only way to get Windows-only Steam games working on Linux.
As of late 2020, most games that are still not working are multiplayer games using third-party anticheat systems.
- ProtonDB - User reported compatibility list.
- To do this, click Steam > Settings > Steam Play > "Enable Steam Play for all titles".