Remember that Star Trek episode where the shuttle crashes on an alien planet, and in the process of repairing it the crew discovers that they're surrounded by ten-foot-tall cavemen who don't like strangers? Symmetry, released in 2018, is kind of like that: You have to manage the crew of a crashed spaceship, keeping them alive and sane while they try to fix their ride and escape from a world that's actively trying to kill them.
I thought it looked potentially very interesting before it came out, although I never got around to actually playing it. Now I'm getting another shot, as GOG is giving it away. Just hit up the GOG website and click "get it free" on the banner at the top of the page. That's it, you're done. Good thing I'm here to explain these things, eh? You've got until 9 am ET on April 5 to get it.
If you're looking for other things to occupy your time this weekend (and I suspect you might be), GOG has a number of sales on the go too, including an 85% markdown of the Homeworld Remastered Collection and the prequel Deserts of Kharak, 75 percent off EA's outstanding survival-horror hack-em-up Dead Space, 84 percent (yes, 84) off the sci-fi exploration sim The Long Journey Home, and 70 percent off Darkest Dungeon—which, in case you hadn't heard, is getting PvP DLC, for real, in May.