There was a show in Discovery channel a little while ago called "Life After People". I think it would do the devs some good to watch this series. It's extremely interesting and could also provide some good lessons in making the Xsyon world. (Available on Netflix online if anyone wants to look it over)

For instance, what if the map exposed a defunct nuclear plant that had a catastrophe hit it shortly after we went into hiding?

What if there was a zoo in an area that housed large exotic beasts that survived in the world without us around?

What about an oil refinery or pipeline?

There would be lots of relics left over by civilization that could very well change the landscape and environment around them without humanity around to keep things in check.