Side note: going to setup the core gameplay first before I go back and touch the story
You are a young person, when you came visit your parents, you found out your Parents (Professors, Inventors) are murdered.
You panic, crying, ( cut to fade scene, play texts like "Police came by but found nothing useful..." "A week later", "You decided to discover the truth yourself", the only thing that looks weird is a solar system drawing your dad was holding when he was dead because he was an Astronomer so it does not look super weird for other people, but you know you have a solar system model in your room. Might means something, but it worth a try.
While you are searching, and trying to find clues. Looking around, you found newspaper saying "your parents (at random university) was working on studying time travel possibilities and made a lot of progress" "AVO ( a company name) failed to conduct time travel trails and went bankrupt" "Today's weather..( just random stuff)", notice the newspaper was from a few years back.