5) Amnesia: A Machine for Pigs

Amnesia: A Machine for Pigs is a thinking man's horror title. You play as a wealthy industrialist who, stricken with amnesia, must uncover the truth behind a mysterious man called The Engineer and a Machine of unknown design as you are pursued by horrifying creatures that are part man and part pig. 

The truth you will uncover, however, will deeply disturb you. The heavily symbolic plot makes great use of its setting and forms its characters and events around the main theme of the selfishness of human nature.

In that, A Machine for Pigs finds its own way to produce despair. 

While not nearly as polished or innovative — and as a result of that, as well-received — as the first game in the series, Amnesia: The Dark Descent, A Machine for Pigs still earns for itself a spot in the horror gaming hall of fame thanks to its stellar writing that is bound to command fear in anyone who plays it.

 
Part man, part beast.