In the majority of the SAS: Zombie Assault series, the mission was to survive a certain number of waves of zombies. However, in SAS: Zombie Assault 3, a new mission was added: Purge mode. Players were to stop zombie nests from spawning zombies by shooting them to death. For beginners, Purge mode is very difficult because the nests have large amounts of health and the zombies can easily overrun the players.In SAS: Zombie Assault 4, however, each level has its own special mission, such as rescuing people or eliminating everything in the map rather than surviving waves of zombies.
SAS 1, 2 and Insane Asylum
As mentioned above, the first games were only about surviving waves. Each game had a different map and players would have to survive for 30 waves.
SAS Zombie Assault 3
SAS3, like earlier games, is about surviving waves. However, instead of one level with 30 waves, there are five levels with 4 waves to start. The waves get longer and increase in number as the player ranks up. Also, there is Purge mode, which can only be played on Verdammtenstadt and Black Isle. In SAS3 Mobile, there are many maps with 5 in each region, these being Europe, North America, Russia, and China. Also, a new gamemode was added in 2012: Apocalypse mode. The objective is simply to survive an endless wave of zombies, which won't end until all players are dead. SAS3 also introduced online multiplayer. In SAS3, 4 players are randomly selected to play one multiplayer mission, with a gamemode the player selected.
SAS Zombie Assault Tower Defense
"This narrow and dark street is a good place to ambush the zombies, you should also be able to get some men onto the rooftops to keep them safe."
Mean Street, As it's name states, Is a street. With 5 elevated positions for SAS soldiers, A note that says "BEWARE" at the bottom left, At the top middle there are several cars, useful for blocking, and the exit at the lower middle right.
"The zombies have tracked down this human refuge camp in the mountains. It should have been safe, but it isn't. Luckily it should be easily defended... for a while."
The map of Sub-Zero appears to be the entrance of some sort of a survivor camp, Which can be seen through the exit at the right. There are 6 elevated positions for the SAS soldiers, And, unlike Mean Street, There are two entrances.
"Stop the zombies from getting through this cramped warehouse to the exit, funnel them in, trap them, and destroy them."
Shop Til you Drop
"Fighting in the open is normally a poor choice when outnumbered, but this time we have no alternative. Use turrets and sandbags to guide the zombies into killzones of your own design."
"We are at risk of being surrounded, the Zombies will come from multiple directions through this vegetated hilltop. Choose your positions carefully."
"Chaos ensued after zombies invaded the stadium. The surviving people have exited but we need to hold off zombies here so they don't spread to the suburbs."
Cleanup on Aisle 13
"Zombies are swarming into the department store from the western wall - stop them from getting past you and into the mall at all cost"
"Use the natural choke points to set up a killing field and defend this high priority position. If things go south, well, let's just say that there won't be any point in extracting you."
SAS Zombie Assault 4
In SAS4, all 9 maps have different missions:
- Onslaught: Survive 6 minutes of zombies and kill everything in order to escape the space station.
- Vaccine: Retrieve and bring the vaccine to the dropship within the time limit.
- Survivors: Rescue as many survivors you can, 60 total, and defeat the boss.
- Zombie Pods: Kill everything in a supermarket while investigating strange pods.
- VIP: Rescue a VIP from his zombie-infested house and bring him to the drop point without letting him die.
- Power Out: Repair all switches and destroy all Loaderbots to return power to a blacked out hospital.
- Last Stand: Defend against 8 waves of zombies and survive without letting too many zombies get past you.
- Ice Station: Start off defending an abandoned mining base, then escape it and fight the boss after you survive the truck ride out of the mining base.
- Meltdown: Shut down 3 reactors in a nuclear plant before the plant goes into meltdown.