The biggest thing that sold Prometheus as a film and a viewing experience was the fact that Ridley Scott confirmed that it would take place in the Alien universe, and would be a prequel to one of the best science fiction horror thrillers of all time. This rejuvenation of a franchise that seen epic highs (Aliens) and huge lows (Alien: Resurrection, sorry Joss Whedon) caused mass fan hysteria and jubilation. However, while Prometheus were certainly playing in the sandbox of Alien, it only hinted ambiguously at plot elements and parts of the overarching mythology, rather than giving the fans what they wanted: answers. There are several deliberate plot elements established in Prometheus that not only hint at the connective story to Alien, but all but confirm it without actually doing so - the Prometheus lands on LV-223, a sister satellite moon to LV-426, the moon on which the 'Nostromo' touched down on, the Space Jockey's backstory is revealed but only partially and through inference and the viewer using their own nous to bring the threads together. However, it's also been left so open-ended that it affected the narrative payoffs of the story. Prometheus 2 needs to connect, one way or another, closer to the Alien story, and give people the answers they deserve as ardent fans and moviegoers. Scott and his team have to give the viewers and fans enough information and resolution to those answers so that it not only fulfils their need for a compelling story also properly connects to events that have already happened in the moviegoers' eyes, like connecting jigsaw pieces together until it resembles a completed picture. This doesn't have to be a big expansive two-hour exercise in filling in every gap left - Scott is a master at science fiction horror, suspense, and the exploration of intelligent themes - but Scott also has a fantastic opportunity to set the stage for his first great masterpiece, fitting everything in so that the universe he created in Alien makes sense and does so in a fantastic, terrifying, utterly genius way. He just has to do it now. Over to you, Ridley. Make us proud.
