Update: They changed their minds on this, they've put the native version back up. See here.
Original article below:
It seems Transhuman Design have removed the Linux version of BUTCHER after users reported issues, opting instead to ask Steam to add it as an approved Steam Play title.
Announcing it on Steam, they said this:
Sadly, BUTCHER spontaneously stopped working on Linux. The most likely cause seems to be some incompatibility between the old Unity 5.6 Linux builds and new GPU drivers.
Since moving the codebase to a newer Unity version is potentially a titanic task (including testing, debugging, and hair-pulling) and the sole programmer of the game is tightly involved in another project to keep him afloat, we decided to request the game to be whitelisted as fully compatible with the new Steam Play feature.
Before it's officially accepted, you can try it now yourself and hopefully enjoy your game working on Linux again!
After digging into the Steam forum, I came across this forum topic started in August, where four users mentioned trouble starting the game. That doesn't seem like a lot of people to make such a big decision, but it's understandable that with a tiny team and little time they're trying to make it so Linux gamers still have a good experience. Probably a good case for Valve to allow people to have a choice between native and Steam Play's Proton.
Obviously the problem with them doing this, is that it no longer shows up as a Linux game on Steam, that is until Valve decide what they're going to do about showing Steam Play on store pages (if anything).
I'm pretty curious to know what the actual issue is here. Is it Unity once again messing up in their older builds, is it a driver update that broke it? We know so little.
What do you think about such a move? Keen to see some thoughts on this.