[Major spoilers ahead for Strange Exit!]
Tidal locking is a fascinating phenomenon. Take our moon as an example: it always presents the same face toward Earth. When you look up at the moon at night, you always see the same “man on the moon” face looking back at you. That’s because the moon is tidally locked to Earth. The Earth’s gravitational pull has slowed the moon’s rotation on its axis over time, so that the moon rotates on its axis once every time it rotates around the Earth.
Tidal locking can also happen to planets that orbit close to a star. The star’s gravitational pull on the planet can “lock” the planet into place so that the same side always faces the star. What would life on such a planet be like? One side of the planet would be always in shadow, cold and frozen, while the other side of the planet would be always lit by the scorching light of its star. Not the best conditions for life to thrive!
But life could exist at the “terminator,” the band between the light and dark side of the planet, which lies in perpetual twilight. In Strange Exit, the world at the heart of the sim represents the conditions on a tidally locked planet. One end of this world is a dark, icy ocean, while the other end is hot and dry. The shelters sit in the twilight area, where humans would have the best chance of surviving.
Lake and the other survivors could find a way to live on the tidally locked planet represented in the simulation. They could make their shelters on the terminator, between the light and dark sides of the planet, where it would seem to be always morning or evening. The plants here would probably have dark foliage in order to adapt to this low level of sunlight. Any animals might use a type of vision best suited to this dim light. With any luck, humans could also find ways to adapt to such conditions.
To learn more about tidal locking, check out Astronomy.com.