This article describes a feature in the first Apocalypse Rising
The Nomad Badge is a badge awarded to those who kill at least 750 zombies, and survive for 30 days.
This badge is the hardest out of the survivors badges to obtain.
"Awarded to those who kill at least 750 zombies, and survive for 30 days. You must accomplish this all in one life, and you cannot earn this badge in a VIP server."