One of the, if not the best game ever made.
There's nothing quite like it, not even any of the newer Fromsoftware games come close to the world and the atmosphere that Dark Souls 1 is able to deliver.

-Exhilarating Boss fights
-Fun exploration
-Huge variety of different weapons to try
-Deep story
-It doesn't hold your hand

It's the whole package, great gameplay, world design and story. I mean what else can you ask of a game?
Especially one that originally released in 2011.

Let's hope that the stigma Dark Souls has for being "just a hard game" goes away someday because it is so much more than that.
There certainly are games that are hard just for the sake of being hard, but Dark Souls is not one of them.
Praise the sun and don't give up skeleton! Lordran awaits.