Blake is correct that sourcing is not needed for the average plot section. But sourcing it has been a practice within the VG project for a couple of years now. The obsession to source plot sections in video games stems from the project's push to get articles to FA status. Among the laundry list of complaints and objections we encountered at FACs, sourcing was one of them. The idea was to source everything to be better safe than sorry.
In short, adding proper sources to the plot section is never a bad idea, but there's no need to dig extensively to do so. ( talk )