Currently Online 
Guessed by @Mnementh
This was a difficult one to rank, because, well, it's largely unlike anything else on this list. Starting with it being a survival horror game, a genre I'm very much not into, and this game solidified just why I'm not. It was extremely difficult for me to finish, not because of actual gameplay difficulty (though it was pretty hard too), moreso because just the thought of booting it up and continuing the journey was a monumental challenge in an of itself. The first five minutes of every play session had me thinking of "accidentally" hitting that Alt+F4 and go do something nicer with my time. But ultimately, I persevered, and man, what an incredible game.
I don't talk about it much here, but Alien is one of my favorite films of all-time, and this game pays homage to it with an incredibly faithful atmosphere that totally captures the feel of the movie, without coming off as a rip-off or unoriginal. It truly feels like you're living the film, only it's a different story that also has significant ties to the original material, expanding upon it quite a bit in the process, and without taking any of the magic or mystery away.
And if the movie was scary enough, the game is something else. It was thoroughly terrifying sneaking through the corridors of the Sevastopol, frantically checking the motion tracker every two seconds in hope that the alien didn't hear my footsteps - never mind when you have to hack a device or break open a door, leaving yourself completely vulnerable for as long as it takes, and it usually takes longer than it needs to, because you're too tense to do even the most basic of tasks effectively. The audio design is incredible too, and plays a big role in making the alien scary, as well as helping you understand where it is and how it's moving - that is, after a learning process. And every time you hear that beeping of a telephone, the desperate moments before you find it, the three-second wait that feels more like three decades, and then finally, the relief of saving the game - it usually comes with another look at the Alt+F4 keys.
In other words, it does its job fantastically well as a survival horror game. If you're into the genre, it's a bit of a must-play, and it's probably also a must-play for those like me, who are not into the genre but are into Alien. Isolation is fantastic, it's terrifying, it's beautiful, and it's the best thing to come out of this franchise since the movie that inspired it. I don't know that I ever want to play it again, but having conquered it once was amazing and unforgettable.
