Before we understand what Steam Play is, let’s check some prerequisites…
Wine, originally an acronym for “Wine Is Not an Emulator”, is a compatibility layer capable of running Windows applications on several POSIX-compliant operating systems such as Linux, macOS and BSD. Instead of simulating internal Windows logic like a virtual machine or emulator, Wine translates Windows API calls into POSIX calls on-the-fly, eliminating the performance and memory penalties of other methods and allowing you to cleanly integrate Windows applications into your desktop.
Wine is an open-source technology and can be downloaded for free. CrossOver is commercialized version of Wine from CodeWeavers.
Proton, a tool released by Valve Software and CodeWeavers, allows games which are exclusive to Windows to run on the Linux operating system. It uses a custom version of Wine as well as additional libraries developed alongside it to facilitate this. These include Direct3D to Vulkan translation layers, namely DXVK for Direct3D 9, 10 and 11 and VKD3D for Direct3D 12.
Vulkan is 3D rendering API, successor of OpenGL. Vulkan offers lower overhead, more direct control over the GPU, and lower CPU usage. The overall concept and feature set of Vulkan is similar to Mantle later adopted by Microsoft with Direct3D 12 and Apple with Metal.
Steam Play is compatibility layer built into the official Steam client that allows you to play games from your library that were built for other operating systems. For example, Steam Play uses Proton to allow Linux users to play Windows games.
DOSBox emulates an IBM PC compatible computer running a DOS operating system including many IBM PC compatible graphics and sound cards. This means that original DOS programs and games are provided with an environment in which they can run correctly, even though modern computers have dropped support for the old environment.
Boxtron is Steam Play compatibility tool to run DOS games using native Linux DOSBox. It enables you to play games on Linux that don’t have a Linux build setup on Steam only this is for DOSBox games.