Mass Effect takes place in a massive and diverse universe across two galaxies. Part of the appeal of the first Mass Effect game was the premise that humanity discovered intergalactic society, and found itself at the bottom of the social hierarchy because the other aliens were far older and more established on the galactic stage. This was a barrier for Shepard to overcome, and in doing so they learned about the different alien races, their culture, and history through the people who joined them on the Normandy.