Not just Proton: Getting to know Valve's new SteamOS compatibility layers

For Griffais, the goal is for gamers to be able to consider Arm-based hardware without having to say, “Oh this device is good, and the specs are good, the value is good, but I have to leave a portion of my catalog behind if I’m even considering it.”

The droids you’re looking for?

The second new compatibility layer hitting Steam is Lepton, an expansion of the pre-existing Waydroid project focused on getting standard Android APKs to run on SteamOS through a software container. This layer is especially necessary for the Steam Frame, since many of the standalone VR titles players will be running on the device were originally designed for the Android-based Quest headsets.

The official logo for Valve’s “Lepton Development” tool looks, uh, thrilled to be here.

Though many of those titles already had Windows ports for compatibility with previous SteamVR headsets, many current Steam Frame titles seem to simply be running as APKs through the Lepton compatibility layer. VR.org dug through Steam metadata this month and found that 52 of the first 120 “Great on Frame” games run on the Steam Frame as Android executables translated via Lepton. That includes the first trio of Steam games listed on the storefront without any Windows, Mac, or Linux builds (note the lack of desktop system requirements on the store pages).

“They’re really VR developers who want to publish their VR content, and they’re porting a mobile VR title where they’re already familiar with how to make those APKs,” Valve engineer Jeremy Selan told The Verge last year. “They are now free to bring those to Steam, and they’ll just work on this device.”

Does that mean other Android developers could throw their APKs through Lepton to get generic Android apps (and non-VR games) running on SteamOS? Valve’s Lawrence Yang told the Verge: “We’ve never disinvited people from doing that” but added in practically the same breath, “We are a games company and we are focused on games.”

Whether or not a wave of Android apps start coming to Steam now, we’ve definitely come a long way since Valve was asking developers to create their own bespoke Linux ports for the first version of SteamOS. Now maybe Valve and the community can finally get to work perfecting a compatibility layer that will run Apple II games directly on SteamOS.