Love transcends time and space in Interstellar. But in Dark, love is the guiding force which maintains this time and space loop.
(There might be some spoilers for those who havent watched first two seasons)
"The question is not when, but what world" - with this ended the second season. And it left everyone with nagging doubt that whether this was a ploy by the creators to extend the plot, as there were still equal number of unanswered questions at the end of season two, as it was at the end of first season. The addition of another world defintely led to more confusion superimposed on already existing one.
The execution of the concept of time travel is simply different and beautiful. If any had watched and marvelled at Predestination movie, then Dark is 10 times that. Name any sci-fi movie ever released based on time concept (Donnie darko, back to the future, to name a few) and you will find it in Dark, only much better. The complex weaving of characters in first two seasons left us bewildered whether this knot can ever be unravelled. And unravel it does!!!!. The penultimate episode just beautifully explains the ever repeating saying in this season - "The beginning is the end, the end is the beginning". And the ultimate episode is the kind of closure one was hoping to see in so many other 'most watched' series.. It kind of perfectly finishes the series.
Its just hard to imagine how immensely hard it would have been to write down the entire plot in the beginning..since all the things from the first season have been well connected. The entire series would have been scripted initially itself.
Anyways, hats off to the writers and director for bringing up such an engrossing story!.