10. Outlast 2
When Outlast first released in 2013, it took the gaming world by storm. Not only was it a successful game, but it helped to bring out the popularity in the video game horror genre, and for that, it will always be remembered fondly. Outlast 2 also had a big debut, although not as culturally significant, the game was well-reviewed and respected.
A third game in this series would pump some adrenaline into the horror game genre, and the studio says it's something that they hope to do. But as of the moment, the only Outlast project in the works is Outlast Trials, a multiplayer game. It acts as a prequel to the first two entries, and although it looks intriguing, it's a shame that there is no current direct single-player sequel in the making.
Although we are not in a position in which we need more single-player horror games, it does seem as though Outlast's single-player outings have been proven to work, and it's unfortunate that we won't be seeing a new one for some time.