Various is the correct author for any book with multiple unknown authors, and is acceptable for books with multiple known authors, especially if not all are known or the list is very long (over 50).
If an editor is known, however, Various is not necessary. List the name of the editor as the primary author (with role "editor"). Contributing authors' names follow it.
Note: WorldCat is an excellent resource for finding author information and contents of anthologies.
I have not played the game, but did enjoy this collection of stories. Lots of good zombie action and I like the cast of characters. Each main character gets their own chance to shine. And despite their words, they do work well together. Made for zombie lovers.
It's almost funny when they mention that they've tried to escape several times, but something always threw a spanner in the works. So that's why there are several scenarios in the game. These four sure are unlucky. Still, reading about the characters you can play as in the game is less interesting than shooting zombies yourself. The story has flashbacks of the moments each of the characters first learned of the outbreak. It's not a page turner and doesn't reveal anything pivotal about the main characters who are little more than regular people with greater skill in firearms usage.
After barely surviving on their own, Bill, Francis, Louis and Zoey are picked up by the military. Instead of joining other survivors in Camp Echo, they are treated as prisoners and tested medically. Even more unfortunate, the soldiers aren't fully commited to their superiors. It's a recipe for disaster. There is little hope to be had in the world due to the threat of being overwhelmed by zombies around every corner. People easily turn on each other in this uncertain world.