Gaming on Linux
Linux is not a traditional videogame platform but is capable of running most games ever created either natively, through compatability layers/binary loaders or via emulation.
- Darling (MacOS compatability layer)
D9VK may merge with DXVK in the future although DXVK will not merge with WINE because the former is written in C++ and the latter in C.
Most modern emulators provide Linux builds with a few exceptions. The proprietary Wii U emulator Cemu is currently exclusive to Windows but runs well under WINE. For native Wii U emulation try decaf-emu. Xenia, an Xbox 360 emulator is currently putting Linux on hold while switching development from Vulkan to DirectX 12.
The [Emulation General Wiki http://emulation.gametechwiki.com/index.php/Main_Page] is a useful resource for the subject.
The first commercial Linux title was a port of DOOM in 1994 followed by ports of other games from the id software catalog. Other than that about two dozen games were ported to Linux by studio Loki Entertainment before declaring bankruptcy in 2001. liflg.org maintains scripts to install these early titles on modern Linux systems with the original CD-ROMs.
Support from Valve
Steam has been available on Linux since 2012. The only other notable publisher to support Linux is GOG although they havn't ported their GOG Galaxy client yet.
Valve has been pushing Linux adoption for many years. Microsoft has failed to launch a succesful game store on two occasions, first with GFWL and now with the Microsoft Store. Valve rightly fears that Microsoft will in some unscrupulous way leverage Windows dominance to capture the market.
Valve secretly funded the development of DXVK. The project progressed so rapidly that many suspected a monetary interest. When Valve announced Proton this suspicion was confirmed.
Valve has also funded other projects in the Linux ecosystem such as kwin and Mesa.
There are some bumps in the road for gaming on Linux. For instance, Metro 2033 and Metro Last Light were released on Linux but Metro Exodus was not. Perhaps not so coincidentally the developers signed an exclusitivity deal with Epic Games which does not support Linux on their store.
When Microsoft acquired Mojang they proceeded to rewrite Minecraft in C++ for the "Play Anywhere" edition, a misnomer for sure as it cannot be played on Linux (although the Java Edition is still supported).
Vulkan is a modern cross platform graphics API that competes with DirectX 12. It is the successor to OpenGL. Games using Vulkan are not always ported to Linux but generally perform well under WINE. Linux users are fighting on the same side as Vulkan.
Many games ship with DRM like Denuvo which is unsupported by WINE. It's up in the air whether this is a bug or a feature.