According to a report by Linux gaming site Boiling Steam, 72% of the current top 50 games on Steam can run on Linux, either using Proton or running natively. Some of the unsupported games should eventually work with Linux due to Valve's efforts to enable a vast roster of games for its forthcoming Steam Deck handheld console, but anti-cheat programs have hindered progress on Linux-based systems.
The Top 50 list of Valve's Steam chart includes games with the most concurrent players over two weeks. So rather than sales, whatever game is played the most gets a spot on the chart. Unsurprisingly, these include titles like CS: GO, Dota 2, PUBG, and GTA V.
Several game titles in the top 50 won't work in Linux merely due to anti-cheat engines, like BattleEye and Easy Anti-Cheat (EAC), that require privileged access to a kernel module, which Linux forbids except under certain circumstances. Valve says it's working to address this issue before launching the Steam Deck, which would help fix compatibility issues with eight unsupported games on Steam's top 50 list.
That isn't the only work needed to enable Linux compatibility, though. Valve's Proton project offers a compatibility layer that translates Windows-specific OS calls into Linux-specific system calls and translates APIs like DirectX into OpenCL and Vulkan. This project is at the heart of Valve's upcoming Steam Deck gaming console, which runs a Linux-based operating system.
Given that the Steam Deck is said to start shipping by the end of 2021, it's no surprise that Valve has been working on bringing support for as many titles as possible to Linux and testing titles that already support OS. With 36 games out of the current top 50 supported, hopefully the remainder is well on their way to better non-Windows (or MacOS) support.
As much as we anticipate seeing broader support for more and more games on Linux, it's a tough task that requires a lot of development to get right. Proton needs to translate API calls, and often a game is very complicated to work with, requiring a lot of translation to happen nearly instantly. Hopefully Valve is taking its time to get things right and ultimately deliver a handheld gaming console capable of running most of the Steam library in a way that you won't be able to tell whether it's using a compatibility layer or running natively.
We recently reported that Linux gaming reached a 1% share in the Valve steam hardware survey, indicating that Linux gamers are present in strong numbers already. They just need proper software to run games on their preferred OS. As Valve broadens support for additional games and anti-cheat engines, we expect that number to grow, no matter how successful the Steam Deck is.
The marketing is STRONG with this item. Remember... Steam machines!
I would recommend that you dualboot at least to begin with. That way you can compare the usability and performance between SteamOS and Windows. One thing to consider is that SteamOS will have a unique feature not available on Windows and that is fast-suspend-and-resume of games similar to a feature present on Xbos S as I understand. It will let you suspend any game mid-play with the touch of a button and then resume fast and continue where you left off. Google "steam deck fast suspend resume" for more info about this feature. It has required custom development in the whole graphics stack including the Linux kernel in cooperation with AMD to get it working seamlessly. That will simply not work the same way with Windows on the Deck, since it will then work the same as ordinary Steam on a Windows laptop. Just so you are aware.