this post was submitted on 20 Nov 2025
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The runtime is not Steam itself. That's more or less independent from the runtime. The runtimes are a collection of libraries that developers can develop against without having to include them themselves.
Kind of similar to the Visual C++ Runtime on Windows.
I know what a runtime is, but I'd like to check which version of it I'm running. 🙂 Wouldn't be very difficult but I'm this instance I don't know how.
The runtime is for launching games, not Steam itself. You can check the runtime selection in Compatibility tab of Steam and of each game. If your Steam Flatpak install doesn't work, the issue is likely somewhere else.
I'd suggest trying to launch the flatpak from the terminal and seeing if there's any strange logging.
Already did that but I couldn't see anything that I could recognize as abnormal. The "Connecting" window shows up, actually. But it just stops loading for a second and then it just says "Reaping pid" in the console and it closes the process.
Hold up, are you talking about the compatibility layer, "Proton"? I'm not sure that's what we're talking about here. Proton is up to version 9 and 10, not 4.0.
You can select Steam Runtime Versions in the Compatibility tab too, separate from Proton versions
Oh okay, I guess that's in the main Steam settings, not per game as the other person suggested.
You can select it per game as well,
steam runtime 3.0and now presumablysteam runtime 4.0should show up in the same drop down menu next toproton 1.0,proton 10.0in the compatibility optionsAnd also, should be noted, only for games with a Linux native version
oh I was wondering what the difference was 😅
No, it is a per game setting. When your game is a native Linux game it will use one of the Steam runtimes. If you had a Linux native game and selected Proton instead of a Steam Linux runtime Steam would download the Windows version of the game.
With Linux native games you usually don't have to touch this setting.
Right but you can't change the native runtime per game. You can only change the compatibility layer (Proton) globally and per game. The runtime is static obviously, and either used or not used. I'm guessing Proton bypasses the native runtime by having the game interacting with it? Or maybe it is a translation layer? Both? Anyway, doesn't matter. 🙂 What wasn't the problem.
But I'd still be interested in how to check which version I have, just to know.
Edit: hold on, does the runtime show up in the same list as Proton versions? That would explain what you all are talking about. And only for native Linux games. That's why I haven't seen it before I guess.
The runtime is a container with libraries. Proton always runs inside the container by design. The runtime ensures the software environment is predictable, Proton ensures Windows binaries can run (by handling Windows API calls)
So you can use those to develop on a platform and be sure that it work on the other too? Is this runtime steam-indipendent?
Yes. Exactly.
Older stuff here: https://github.com/ValveSoftware/steam-runtime
Newer stuff here: https://gitlab.steamos.cloud/steamrt
The dev guide within that gitlab repo confirms that it can be used sans Steam: https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/slr-for-game-developers.md
This applies to the new runtime as well: https://gitlab.steamos.cloud/steamrt/steamrt4/platform
Oh that's cool, thank your for the link too
idk about that, but it's called the Steam Runtime because it's the library files for running Steam. so I'm not sure what context you would use it in that didn't include Steam, since it's used for everything Steam does from connecting you to your friends in multiplayer games, to notifying Steam users that it's their turn in asynchronous games.
if the game wasn't run from Steam, it probably wouldn't need or want to use the Steam Runtime.
No, it's for running games on Linux. Steam will probably use the libs as well for its own functionality. But the main use is for game developers to target specific libraries so that they are independent of the user's distribution.
And they can indeed be used outside of Steam as well. I sometimes use it to link in specific libraries for other games. @Axolotl_cpp@feddit.it
Thank you!
I stand corrected then