Been having issues with people reporting that SteamOS / SteamApp won't start the application, but that it will run in the console. I've been updating the Linux version every few days when new information is provided by testers or by digging through YoyoGames website.
This latest version was built on a "physical" Ubuntu 18.04 desktop. Previous versions had been built using a VirtualBox. Not sure why this is any different, but it is the only one YoyoGames will support. Please let us know if it is or is not working properly if you use Linux / Ubuntu / SteamOS.