A strategy/shooter game where 24 stranded soldiers fight against a zombie horde to secure supplies, rescue civilians, and defend their city. 

Primary inspirations: State of Decay, Road of the Dead, Left 4 Dead, Infection Free Zone

The city/world:
-Make the city as big as possible
-The city has been lost, the hordes having overrun and slaughtered (nearly) all defenders
-the only surviving humans are the immune and the immunized
-the military was crippled, as was everyone else, as the vast majority of all command levels were either zombified or killed by zombies

Shooting:
-Realistic gun mechanics
-Guns are actually accurate
-First person

Zombies:
-Zombies take multiple shots to kill, how many depends on gun and caliber (~8 shots to head from M16A4 would be enough)
-There are a lot of zombies because death tolls were absurdly high and the city was ground zero
-If a zombie reaches a human, that human is tackled and torn into, resulting in death without help
-there are no special zombies
-Zombies always sprint and call nearby zombies

Strategy:
-Strategic map detailing notable locations
-Player sends expeditions to notable locations
-Player controls squad leader and commands the squad
-Friendly AI has to be very smart to keep up with the player
-6 soldiers per expedition

Survival:
-Soldiers and surviving civilians are either naturally immune or vaccinated against zombie disease
-Soldiers can still get sick from normal diseases, which they can catch from zombies who carry them along with the zombie disease
-The Soldiers are good at stretching supplies, but they can't go forever without resupply