Looks like this has been brewing for a while. Game unceremoniously pulled from Steam.
The publisher, Grip Digital is (as of early June) undergoing some odd changes. https://twitter.com/Grip_Digital/status/1278635421954703362
"Hi everyone, sorry again for a silence here. There was a crucial change in Grip's structures and business vision and due to this we honestly have lost our access to the Twitter accounts. Sounds silly but sometimes the simplest explanation is the fact :)" https://twitter.com/Grip_Digital/status/1278637907197247494
"Due to this, we also will be no longer able to support our old titles. We appreciate all of our fans and customers but the vision and business strategy has slightly shifted. Our teams and businesses grows and we need a new space to breath. We will inform you soon :)"
Reeks of Desura.
Seems Mothergunship is currently safe on the platforms its on but then Grip is merely listed as a co-developer (money input i would guess), and Joe is usually rather independant.
Edit: their website is now a "coming soon" and "hiring" holding page.