I'm picking up with a years old save, and I had a brief moment of "what on earth was I supposed to be doing?"
Prime 2's "hint" system that calls the user to the next place to progress the story.
I found that hint system to be helpful; even necessary to progress. I obtained an upgrade and the next world was far away, in another map, in the dark world. I would have found it eventually, probably, but as a parent with limited time, a guiding light was helpful.