After seeing End of Sky a third time, I have two small observations regarding music.
1. The music that plays whenever Genji shows up is TERRIFYING! Go listen to the Witch Theme from Left 4 Dead. Sounds exactly like that to me.
2. There’s an orchestrated instrumental version of Higher Ground that plays in a few scenes. Doesn’t seem like the kind of song that’d suit that kind of music but it’s beautiful and heartbreaking.