Hotline Miami is a brutal top-down shooter where you're instructed to kill a whole bunch of people and you really don't know why. The game is incredibly unsettling, between the genocide, the creepy music, the graphics that look like a terrible VHS recording, the terrible sense of increasing loneliness and desperation, and the sense that maybe all of it isn't real, even by the game's standards.
The gameplay is tough. The action is frantic, since one shot kills you and enemies move quickly, yet requires a lot of planning as you decide how to take on heavily-guarded buildings. The harder battles are ridiculously difficult. The sound is creepy and very fitting. The graphics are simple 2D, but the aesthetic is also unsettling. The controls are tough to get used to, but ultimately work most of the time. The story's somewhat minimal, but the story that is there is very interesting.
I think this game is worth the price tag, and if this looks interesting to you, I don't think you'll be disappointed. If you enjoy it, there's a lot of replay-ability here too. Definitely get it if it's on sale. The soundtrack is very good, but it's not exactly feel-good music. Either way, consider picking up the soundtrack too.