Little Green Men are making their space title Starpoint Gemini 2 free for the next 48 hours. This is a “free to keep forever” type deal, rather than a temporary Steam free weekend. If you claim it within the next couple of days it’ll be in your account forever.
All you need to do is visit the store page for Starpoint Gemini 2 (linked just above) and click the button to install it. Their next game, Starpoint Gemini Warlords is coming out on 23 May, so this is a gesture of generosity and publicity rolled into one.
From what I played, Gemini 2 was a commanding lone trading ships and taking RPG missions type experience. Warlords is introducing some strategic and 4X elements on top.