Well according to the latest email, May 1st is the release. So this will be live at 12am PST on Tuesday, May 1st.
We also reached out Snapshot Games to confirm a Linux. According to our email reply, it looks like the build will have support.
Linux release live in Backer Build:
“We will be supporting Windows, Linux and Mac OS.”
We will be releasing the Windows version at Midnight PST. There may be a slight delay on Mac and Linux as we're tracking down a few stubborn, pesky bugs.
— Phoenix Point (@Phoenix_Point) April 30, 2018
Details from the post:
“We would once again like to apologise for the 24 hours delay in the release of the Backer Build. We had originally planned for the build to release at midnight PST on April 30th. Unfortunately, due to an internal miscommunication and some confusion over time zones, the development team were working under the impression that they had 24 hours longer. We don’t want to rush this. The team have been working hard through the weekend to complete Backer Build One and squish as many bugs as possible.
Backer Build One is available to anyone who backed Phoenix Point during the Fig campaign at the “Digital Extras Edition” ($40 USD Tier) or higher. It is also available to customers who pre-ordered the “Luxury Digital Edition” ($50 USD) or higher. The Backer Build may be listed in your package as “early access” or “pre-alpha access”.
We're still working on it. We're currently in testing to make sure the issues are resolved (and check we haven't introduced any more!). Sorry to keep you waiting. Won't be too much longer though.
— Phoenix Point (@Phoenix_Point) May 3, 2018
You will play as the New Jericho faction, controlling 2 Assault soldiers, 1 Sniper and 1 Heavy. The Backer Build includes the free-aiming system. Also introduced at EGX Rezzed and the inventory system which we have not yet showcased.
Backer Build One is a pre-alpha build of the tactical portion of the gameplay. It contains the demo map which you may have seen from the previous events that we attended. It also includes procedurally generated maps.”
Phoenix Point Narrated Demo Gameplay
Phoenix Point is set for a Q4 2018 launch via Steam. Since the games is in development, we will have support for Linux, Mac and Windows at launch.
Phoenix Point comes from the minds of Julian Gollop, veteran designer of the original X-COM games. And David Kaye, the founder of Gaming Insiders.