Soma (opens in new tab), the atmospheric sci-fi horror game from Amnesia developer Frictional Games, is free to keep to GOG right now. The offer ends on Sunday at 3am PT/6am ET/11am GMT, and you can grab it here (opens in new tab).
It's worth playing, no matter what your tastes: its twisting, cerebral plot made our list of the best stories in PC gaming (opens in new tab) earlier this year, and it's also on our best indie games list (opens in new tab). You'll enjoy it even if you hate horror thanks to its monster-free Safe Mode, which was added last year (you can read Andy's interview with the devs about it here (opens in new tab)).
If you're interested, you should read Andy's full review (opens in new tab)—he called it a "masterpiece of audio and visual design", and said its underwater base was "one of the most fascinating, atmospheric spaces I’ve ever explored in a game". High praise indeed.
You can browse all the discounted games in GOG's Winter Sale here (opens in new tab).