Complex sentence: The player controls a faster-than-light (FTL) travel capable spacecraft belonging to the Galactic Federation, which is on the verge of collapse after losing a war with rebel forces, chiefly human in species.
Split into simpler sentences: The player controls a spacecraft capable of traveling faster-than-light (FTL). It belongs to the Galactic Federation, which is on the verge of collapse after losing a war with rebel forces, chiefly human in species.