Full description is in the headline. It launches nicely without "-vulkan" enabled. The Talos Principle works(as the only game). I'm using the Padoka PPA(unstable one) with Mesa 17.0. The current Vulkan package is "mesa-vulkan-drivers_13.0.3-1_amd64.deb". I use Devuan Ascii with OpenBox and an RX 480, i7-5820k.
In what way does it not work? Does nothing happen at all, show a corrupted intro screen, or give an error message in a pop-up? Also, libgl1-mesa-glx from the padoka PPA should provide radv already. That you have mesa-vulkan-drivers too sounds suspicious to me that something is wrong with your system install. (make sure that the libvulkan/libvulkan1 package is installed and up to date). That said, as you claim Talos works it may work in some way ... It would be great if you could get a steam log (i.e. the console output of starting steam, launching talos with vulkan and exiting again).
Well, to answer your question quickly, nothing happened at all than steam changing my status for a short time. Thanks a lot for your suggestion. I have to apologize for my own incompetence! It seems very likely that I introduced a misconfiguration by upgrading from the stable ppa to the unstable on the fly for testing and I believed that only the package versions had changed. So mesa-vulkan-drivers remained installed and I had two versions at the same time. Dota 2 works very well on a clean, fresh Ubuntu 16.10 with the PPA.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.