In Ring, the classic story we all know from the movies was presented. In it's sequel, Spiral, the whole story was presented from a whole new radical angle. Still full of the dark forces surrounding the first part, but taken to the next level, the level of microbiology.
Half way from Loop - I had no other option that to day "HOLY SHIT!" out loud :D The story just got twisted, wickedly. Now it's closer in spirit to The Thirteenth Floor and Matrix, but still retaining the spooky spirit of the first parts :D Godly :D