Update: They have reverted the Linux version to use Coherent UI 126.96.36.199. This now at least enables it to run with NVIDIA as good as normal. Nice to see a quick fix. Hopefully the next time it will get a little more testing.
Planetary Annihilation Inc continue updating and expanding their massive scale RTS Planetary Annihilation: TITANS with a new major update available.
It includes a new unit, the impressive sounding Horsefly:
Found in the Advanced Air Factory and armed with rapid-fire cannons, it strafes targets to remove all the pesky AA (and fabbers) from the vicinity, while tanking return fire with its heavy armour. Conduct your bombing campaigns in peace once more. It will attack the land, it will attack the sea, and in a pinch it can even attack air.
Along with many other unit balance changes, various client and server improvements, AI upgrades and more. They also made a note about how they also have compatibility with Steam Play so AMD GPU users should now get a working UI.
Sadly though, this major update has caused issues for the Linux version. Historically PA has not worked well on an AMD GPU due to their use of the proprietary UI middleware "Coherent UI". This latest update upgraded Coherent UI, which has resulted in the modern Linux build even on an NVIDIA GPU causing a black screen. You can see their fancy cursor but do nothing else. They seem to be aware of the issue, as noted in their "Known Issues" it states "Modern native Linux may segfault in CoherentUI_Host (try Steam Proton)".
You can opt into the legacy build on Steam via the Beta option, but that will only let you play single-player games. I did try out the modern Linux build (the default) in Steam Play as they suggested until it's fixed and to be blunt, it was absolutely atrocious. I've gone from having a native game run super smooth at well over 100FPS to around 30FPS and a UI that lags to the point that it's just not playable. I've got a really strong PC too, can't imagine how bad it will be for others. There's some chat about it on Steam here, not looking good for others either.
As a big fan of Planetary Annihilation: TITANS and someone who supported it since Kickstarter and then later upgraded to a much higher tier this makes me incredibly sad to see. Willingly pushing out an update that breaks it completely on modern Linux distributions isn't really acceptable.