Alien: Isolation, arguably the best horror game of all time (and one of the top 10 games on PC (opens in new tab)), is available on the cheap for the next three days. Over at Fanatical (opens in new tab) you can buy the base game plus all the season pass DLC for a lick over £8/$11. That's 77% off—not quite a historic low but still a damn good deal, and cheaper than it's ever been on Steam.
Alien: Isolation Collection comes with the main game plus the Corporate Lockdown, The Trigger, Trauma, Safe Haven and Lost Contact DLC. They thrust you into a number of horrible single-player situations and add a couple of new game modes that are guaranteed to scare the pants off of you, including Salvage mode, where you have to venture out of a safe room to find specific supplies.
The collection usually costs £35/$50, so this is a hell of a saving. If you haven't had a chance to play through Isolation and you don't mind being utterly petrified once in a while, then I recommend you pick it up (read Andy's review (opens in new tab) if you want a more in-depth judgment).
And if you don't fancy the DLC, the base game alone is discounted by 77% on Fanatical (opens in new tab) too.