Creating the fictional background for a game world isn't significantly different from creating a background for fiction.
“By 2010, Africa could be providing the United States with as many oil imports as the Middle East.”
“It is long since I could have adventured on eternity, through God's mercy and Christ's merits; but death remained somewhat terrible, and that now is taken away; and now death is no more to me, but to cast myself into my husband's arms, and to lie down with Him.”