If you're looking for a mind-bending sci-fi with extremely clever writing and plot pay-offs, an awesome soundtrack, beautiful cinematography, and an incredible cast, then this is your show! I have heard people compare this to Stranger Things, but in actuality, I'd say it's more similar to Twin Peaks and LOST, with a small helping of Stranger Things. To say more would give away the plot and it's much better of you go in blind like I did. Every single episode of both seasons had me absolutely glued to my TV. There are so many insane twists and turns that will continue to blow your mind. This is a show that isn't afraid to go to dark places (please parden the pun) and there are also storylines and twists that will hit you right in the feels...or the gut. BTW, it's a German show and I would recommend watching with subtitles over dubs for obvious reasons, but whatever floats your boat and makes you watch it. :-) I honestly can't recommend this show enough. Can't wait until the 3rd cycle, AKA: season 3!
*****UPDATE*****
After finishing the 3rd and final season last year, I can confidently say with absolute certainty, this is the greatest piece of fiction I have ever experienced. I may come across as hyperbolic, but trust me, if you watch DARK, you'll understand why so many people call this show a masterpiece.