Defend your fortress from the oncoming enemy waves. Place turrets in locations of your choice on your fortress, creating the best defense possible to withhold even the greatest of attacks.
Your forces were out on a routine patrol and the undead were suddenly everywhere! Your forces were badly depleted in the conflict thus you must continue to do your job and keep the undead population under control until a solution can be found.
Shoot the incoming enemies to protect your base. Collect weapons and turrets that automatically fire on the incoming missiles. Push the turrets around the battlefield to take advantage of their range and abilities.
A mission doomed to fail from its beginning. A lone survivor assumed lost in unfamiliar territory. A cunning enemy bent on long-awaited retribution and fourteen days to the promise of salvation.