I was too lazy to read all of the other replies, but here goes nothing =P
It could be similar to Warcraft 3 in that there is a basic storyline revolving around key characters who you play as or are significant NPCs but you take control of different opposing factions. Possibly including:
Civilians - generic humans, can use basic environment items as weapons. Die easily but have large numbers or are easy to recruit into your forces.
Military - Fewer in number to Civilians but have access to better weaponry, armour and vehicles as well as fortifications. Perhaps you can recruit civilians into the military forces at a cost and only if you have a good image at the time (more to be revealed).
Corporation - The staple villainous corporation that is suspected to be behind any good zombie outbreak. They have private military forces, similar to the regular military but cannot recruit civilians. They are fewer in number to the military and have access to better weaponry but less/worse vehicles and fortifications.
Zombies - Cannot use environment weapons but can use weapons and armour they died with. They can corrupt enemies they have killed to increase the number of zombies and can also 'summon' zombies from graveyards or other places with dead bodies hanging around. Much greater in number but generally slowe moving and unable to use buildings.
Rather than being a game with huge numbers of units on the map at one time it could be smaller scale and slighty more like an RPG in that it is largely story based but also has multiplayer modes that accept larger forces. It would also revolve less around building a base and more around moving across the map, avoiding foes or getting to a target area without dieing. But will involve some of the C&C type stages for the Corporation levels. Each faction will have different play styles as they should function differently. The military can easily fight against the zombies and so will be more action oriented, like the Commando games; Civilian levels are survival and objective based; Zombie levels are more of a bonus but are similar to the civilian levels only with more units and a lot more killing and the Corporation levels are pretty much C&C type levels where you build buildings, train soldiers or hire mercenaries and try to supress revolting civilians or pesky zombies whilst avoiding military attention.
You start with a certain amount of units of various types depending on the mission, usually including your avatar type 'uber-character' that is controlled more than the rest. You might need to explore the environment to recruit more units either by finding survivors, finding miliary facilities and asking for backup or by good old fashioned neck-chomping. Sometimes you might stand no chance directly facing the enemy and so need to run away in a vehicle or to hole up in a building. But you might need to check whether a building is secure before using it if you have the time as there could be enemies inside.
Zombies obviously don't care much for these things and their missions generally revolve around killing all humans on the map within a given time or killing a target human without losing all of you rotting minions.
The Military levels are kind of like the Commando games crossed with Ghost Recon. Possibly with some FPS action, although it would be more interesting and true to the genre (that sounds so camp) if it were purely overhead typical RTS stuff. Most missions would involve having to kill groups of zombies to defend key locations, varying between small and large groups under your command.
It could be similar to Warcraft 3 in that there is a basic storyline revolving around key characters who you play as or are significant NPCs but you take control of different opposing factions. Possibly including:
Civilians - generic humans, can use basic environment items as weapons. Die easily but have large numbers or are easy to recruit into your forces.
Military - Fewer in number to Civilians but have access to better weaponry, armour and vehicles as well as fortifications. Perhaps you can recruit civilians into the military forces at a cost and only if you have a good image at the time (more to be revealed).
Corporation - The staple villainous corporation that is suspected to be behind any good zombie outbreak. They have private military forces, similar to the regular military but cannot recruit civilians. They are fewer in number to the military and have access to better weaponry but less/worse vehicles and fortifications.
Zombies - Cannot use environment weapons but can use weapons and armour they died with. They can corrupt enemies they have killed to increase the number of zombies and can also 'summon' zombies from graveyards or other places with dead bodies hanging around. Much greater in number but generally slowe moving and unable to use buildings.
Rather than being a game with huge numbers of units on the map at one time it could be smaller scale and slighty more like an RPG in that it is largely story based but also has multiplayer modes that accept larger forces. It would also revolve less around building a base and more around moving across the map, avoiding foes or getting to a target area without dieing. But will involve some of the C&C type stages for the Corporation levels. Each faction will have different play styles as they should function differently. The military can easily fight against the zombies and so will be more action oriented, like the Commando games; Civilian levels are survival and objective based; Zombie levels are more of a bonus but are similar to the civilian levels only with more units and a lot more killing and the Corporation levels are pretty much C&C type levels where you build buildings, train soldiers or hire mercenaries and try to supress revolting civilians or pesky zombies whilst avoiding military attention.
You start with a certain amount of units of various types depending on the mission, usually including your avatar type 'uber-character' that is controlled more than the rest. You might need to explore the environment to recruit more units either by finding survivors, finding miliary facilities and asking for backup or by good old fashioned neck-chomping. Sometimes you might stand no chance directly facing the enemy and so need to run away in a vehicle or to hole up in a building. But you might need to check whether a building is secure before using it if you have the time as there could be enemies inside.
Zombies obviously don't care much for these things and their missions generally revolve around killing all humans on the map within a given time or killing a target human without losing all of you rotting minions.
The Military levels are kind of like the Commando games crossed with Ghost Recon. Possibly with some FPS action, although it would be more interesting and true to the genre (that sounds so camp) if it were purely overhead typical RTS stuff. Most missions would involve having to kill groups of zombies to defend key locations, varying between small and large groups under your command.