Perhaps better than any other creative medium, videogames have managed to recreate entire ecosystems of imaginary creatures and presented them in an observable context. Books and movies may offer detailed glimpses of anatomy and behavior, but only in videogames does the observer interact with organisms and experience behaviors first hand.
As you rebuild civilization and restore your people's faith in this sim/action hybrid, you'll find yourself honestly caring about your subjects' helpless lives. Nowhere is their plight more touching than Kasandora, where you help a starving desert tribe grow into a bustling village, only to see an old man die in the dunes. His last wish is for rain, which you grant.