This retells the story starting from before the deletion of the first D-mail (two-thirds of the anime). It differs from the original story by adding more backstory for Kurisu and Faris, adds a conection between them and between their fathers. It makes (partially) sense of the behavior of Nakabachi before the story. For the rest, the scenario is identical right to the end, and completes the character development for Kurisu (and Faris). It's great, even just for reliving the main Steins;Gate story. The quality is on par with the original, even if this added backstory adds unnecessary relations (Hashida's mother, who looks just like Suzuha, indirectly contradictingS;G 0)