As Ars Technica confirmed in May, two months ahead of its official reveal, Valve is about to re-enter the hardware space with its first portable PC, the Steam Deck. This custom x86 PC resembles an XL version of the Nintendo Switch and will begin shipping to buyers by the end of 2021, starting at $399.

Like other recent Valve hardware efforts, the Steam Deck will run a custom Linux distro by default. Today, we're going to explore how Valve's Linux approach will transform by the time Steam Deck launches—and what that will mean for gaming on Linux as a whole.

SteamOS vs. Windows

Although the Steam Deck is capable of running Windows—currently the premiere PC gaming operating system—it won't ship that way. Like Valve's earlier Steam Machine effort, the Deck will ship with a custom Linux distribution instead.

Shipping on Linux cuts manufacturing costs for Steam, insulates the company from competition with the Microsoft Store on Windows, and avoids exposing Steam Deck players to the world's premiere malware ecosystem—which also runs on Windows.

Valve's custom Linux distribution is called "SteamOS." In earlier versions (such as those shipped on the Steam Machine), SteamOS was based on Debian Linux. But the Steam Deck's SteamOS 3.0 is abandoning Debian to rebase on Arch Linux instead.

SteamOS and Debian

When it comes to the features that define a given Linux distribution, Arch and Debian are just about diametrically opposed. Debian aims to provide a relatively generic base and strives for maximal stability via a conservative approach—current stable releases are composed of software that sysadmins tend to describe as "proven" but enthusiasts are more likely to describe as "stale."

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In the quest for predictable stability, Debian relies on intermittent major releases, which require fairly heavy-duty upgrade procedures when migrating from one to the next. This trade-off enhances predictability—although your major release upgrade might encounter problems, it can be scheduled for a time when you're ready to deal with those problems. In the meantime, the software you use on a daily basis changes as little as possible.

Debian is an excellent base for a distribution aiming to provide a simple, stable desktop with a minimum of development work—but SteamOS isn't intended to be any of those things.

SteamOS and Arch Linux

Arch Linux, by contrast, provides neither a generic base experience nor a release cycle. Arch is a rolling release of what might be described as a "build your own distribution kit."

A brand-new Arch installation doesn't give the user a graphical interface at all—because there are myriad options ranging from back-end graphics server (e.g., Xorg or Wayland) to window manager (e.g., Metacity or Compiz) to desktop environment (e.g., Gnome or KDE). Arch doesn't want to assume how the user wishes their system to work, so it makes very few choices for the user in the first place.

Arch Linux is also big on providing the user with the freshest software possible—so rather than provide periodic cohesive releases with a known configuration of known versions of the same software, Arch just updates all its components to newer versions as frequently as possible.

Going with a rolling release means breakage happens much more frequently on Arch than it does on stable distributions—but occasional breakage is an expected part of the Arch ecosystem, which means that resolving breakages is equally expected and planned for.

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Since Arch isn't based on a predictable configuration, its packages are also expected to function in a wider array of possible states—and Arch package maintainers expect to receive and respond to bug reports from that wide array.

What this all boils down to is that Arch is a terrible distribution for an unsupported end user who just wants their generic desktop PC to work. But the Steam Deck isn't intended to provide a generic desktop experience, and Valve clearly intends to sand the rough edges off before its users ever encounter them.

Steam Deck on the bleeding edge

"The main reason [to switch to Arch] is the rolling updates [that support] more rapid development for SteamOS 3.0," Valve designer Lawrence Yang told PC Gamer. Yang says that Arch is a better choice given the massive number of updates, changes, and customizations Valve needs to make in order to provide the best gaming experience on the Steam Deck.

Valve promises that the Steam Deck will run "the entire Steam library" at 30+ fps, so that means a lot of customizations indeed. The Steam Library includes thousands of Linux-native versions of games created by both indie and AAA developers—but that only adds up to about 20 to 25 percent of the entire Steam library.

To play Steam titles without a native port, Linux users rely on a compatibility layer called Proton. Proton support gets another 26 percent or so of the Steam library playable at near-native quality on Linux and about 70 percent acceptably playable.

Unfortunately, this isn't usually as simple as "install Proton, profit." Perusing compatibility reports on ProtonDB quickly leads a user down a bewildering rabbit hole of various distros, third-party repositories, and even different versions of Proton itself.

Careful readers will probably notice that we've called Debian "excellent" and Arch "terrible" for unsupported desktop users—but the Steam Deck isn't a desktop PC, and we're bullish about Valve's choice to rebase on Arch.

To provide "100 percent of the Steam library playable at 30+ fps," Valve will need to continually provide custom-tuned and custom-integrated versions of the latest software throughout the entire SteamOS stack—and that is very much Arch Linux's strength.