In an announcement on the Steam pages for both games the developer said:
It's been about a decade since I first started prototyping a space game - one where you'd start off with a small ship and trade resources. Two games, three game engines and 15,000 copies sold later, here am I with a new life where I don't quite have the time for such work anymore.
Deimos Games will be shutting down this year. Both Helium Rain and Astral Shipwright will be going free-to-play, so that new players can still experience them in the future. As a reminder, both are also open-source, so if you were going to build anything based on these projects, you now have access to free content too. It's been refreshing to see game developers reuse code for their own projects, and I hope that will continue.
I want to thank all players who supported me on this endeavour. I'm truly happy that I was able to share my work with you.
This means anyone can still easily check out their games, and tinker with the code to learn from or make something new. While both games code are available under the BSD license, they do use Unreal Engine, so the code is open source but it still relies on a proprietary game engine - just to be clear on that.
They both go free to play on September 1st.