Steam Play, Valve Proton and Wine - running Windows titles on Linux
Valve has published new beta version of its desktop client for Linux. The most notable improvement is the support of Proton, a Wine distribution with some patches on top. This allows to launch a number of Windows exclusive games to launch under Linux.
Wine is a project whose goal is to port Windows APIs to Unix. Valves has contributed code to run Direct X 11, the native Microsoft graphics interface, applications in Unix through Vulkan, a cross platform graphics API supportes on Linux, Android and Windows.
The 27 titles, which are currently supported with Steam Play and more details can be found in Valves post in the Steam community forum.