NeoGAFs Kent Brockman
But Valve is working to improve SteamOS compatibility ahead of the handheld's launch.
The promise of Valve's new Steam Deck is to let you play your Steam catalogue on the go. But thanks to the particular makeup of the new handheld PC's OS, there may be some major caveats to that promise.
As a Linux-based system, the Deck's SteamOS has a somewhat limited selection of compatible games. To combat this, Valve developed a feature called Proton, which utilises a fork of the Wine compatibility layer, which is designed to help run native Windows titles on the OS—and while this does expand SteamOS's list of supported games considerably, there are some notable exceptions.
According to ProtonDB, almost half of Steam's 10 most popular games—Destiny 2, Apex Legends, PUBG and Rainbow Six Siege—will not work on SteamOS. The culprit, it seems, is anti-cheat software. In most cases games will start up, but their anti-cheat systems won't, leaving you unable to log into multiplayer servers.
Valve does note that the Steam Deck will come with a new version of SteamOS, and is currently "improving Proton's game compatibility and support for anti-cheat solutions by working directly with the vendors". In short, developers won't have to go through hoops to get their games working on SteamOS, but it'd help if their anti-cheat providers did.
We've reached out to Valve for comment on how exactly it's working to improve SteamOS compatibility.