Outlast, the first person survival horror game from RedBarrels, is currently Free on Humble Bundle. The game which was released in 2013 for PC, evolves around Miles Upshur, an investigative journalist who breaks into Mount Massive Asylum, to find its secrets.
The game features stealth and strategy, in that you can sneak past enemies or hide and it also has some parkour elements, But the key feature here, is that you cannot attack enemies. This makes Outlast quite a bit unique.
Be warned however, there are jump scares, which means you will suddenly be attacked when you are least expecting it, so if that kind of gameplay makes you afraid or rage quit, this is not going to be your cup of tea.
So, to get this game, sign in to your account on the website, and head over to the game's page. Click on add to cart, and check out for free, after which you can get go to your account's keys section, and activate the game on Steam.
In addition to Outlast, Humble Bundle is also giving away keys for the game's DLC, you also get the Outlast: Whistleblower (which together is known as Outlast Deluxe Edition), for free. Make sure you redeem the Outlast keys before 10AM Pacific, October 7th, 2017.
You can also download the DRM free copy from your Humble Library.