Playtron are quietly building up their Linux-based PlaytronOS behind the scenes, and not only have they released their first Alpha but they've pulled in another investor too.
Although this game has a Linux-native build available, Steam does not list it as having Linux support. This can happen if a game has an unofficial, unfinished, or unsupported build. You may need to force Steam to enable Proton for the game in order to run properly.
Square where early adopters of Linux back when Steam Machines V1 came out commissioning ports for a bunch of their Eidos (western) IPs. And then they stopped support for those ports when Proton came around
I’m not sure about the others, but I’m pretty sure Hitman isn’t linux native.
As far as I can find on protondb, neither are Deus Ex or Tomb Raider.
I’ve never had any issues running those games through Proton though, so that’s great.
That’s because the IP rights for those games were sold.
According to Wikipedia, Deus Ex MD, Hitman, Life is Strange 1&2, and the new Tomb Raider trilogy all have native Linux ports.
https://en.wikipedia.org/wiki/Feral_Interactive
https://www.protondb.com/app/203160
Square where early adopters of Linux back when Steam Machines V1 came out commissioning ports for a bunch of their Eidos (western) IPs. And then they stopped support for those ports when Proton came around