OtherSide Entertainment sadly won't be getting the Linux version of Underworld Ascendant on Linux at release.
It's still coming though, it just needs a little more time. On Twitter, they mentioned "the Mac and Linux versions around 30-45 days after launch to make sure they have the attention they need". They also said they're looking for testers, so naturally we've reached out to let them know we're available.
Delays happen, sadly. With our market share this is bound to happen, the good news though is they obviously sound quite positive about it. Pushing out a Linux version you haven't had much time to test just isn't a good idea. The Linux version has been available during the beta period, but it seems it has some bugs holding back the full release for us.
More about it:
From the creative minds behind the acclaimed Ultima Underworld®, System Shock and Thiefseries, in Underworld Ascendant®, Paul Neurath and Warren Spector's OtherSide Entertainment challenges you to think creatively in an interactive sandbox environment.