Steam has many features that can be looked at separately, but at its core it’s a package manager. So I would argue an open source alternative comes preinstalled with any Linux distro.
You can find, install, and update games with e.g. Discover or Synaptic.
I don’t think many Steam users would consider them viable alternatives though.










I’m on over 40 Discord servers. And yes I had one for my own group which I moved to Matrix. That still means I’m in over 40 Discord servers. Plus I also run Matrix.