Complex sentence: While exploring PATHOS-2, Simon learns that he woke up in the year 2104, and that in 2103, a massive comet named Telos devastated the surface of the Earth leaving PATHOS-2 as the last outpost of humanity.
Split into simpler sentences: While exploring PATHOS-2, Simon learns that he woke up in the year 2104. In 2103, a massive comet had devastated Earth's surface, leaving PATHOS-2 as the last outpost of humanity.