15Dark Souls 3
There's no way anyone would dare create a list of this nature without mentioning a Dark Souls game. The series is known for its punishing level of difficulty, involved combat system, and the necessity to plot out your strategy by learning from what will be many, many deaths.
Fans of the
series can't seem to agree on which game in the franchise is the most difficult. Some say Dark Souls 2 is the easiest while some say Dark Souls 3 is easier than the second. Many fans say that Dark Souls and Dark Souls 3 have harder boss battles, while Dark Souls 2 has harder areas to traverse and clear.
Either way, the next to impossible level of difficulty in any of the Souls games makes accomplishing even the smallest of tasks a very rewarding experience.