SAS Zombie Assault Wiki

Onslaught is the first mission available in SAS: Zombie Assault 4, taking place in the Kurios Space Station.


The pilot of the ship you're defending, she talks to you through the mission.

A Military Shuttle called "Mantis 12" is trying to depart from a spaceport called "Kurios Space Port" to avoid a zombie outbreak but cannot depart because its drop ramps are non-functional. The ramps will be repaired in 6 1/2 minutes, but until then, the player(s) must fight off the incoming horde of zombies.


It is a spaceshuttle with two door ramps on the right, a large cargo-bay type room with boxes in the middle, left to that is an "emergency forward jumpseat" room, and side passageways on the top and bottom of the central room. It's one of the smallest maps, so be careful of being swarmed or cornered by zombies. However, in terms of being a boss fighting area, it is actually larger, with more maneuverable obstacles to block the boss' movement compared to Survivors.


  • At the 1:45 mark (or 2:30 mark on level 2+), the pilot will drop 2 loot drops on each passageway of the map, just outside the central room, saying "I opened the side cargo bays, i hope there's something useful in them"
  • After At the 0:43 minute mark (1:00 mark on level 2+), the pilot will open the door to the forward jump seats where there's a loot drop and a medkit, saying "I opened the emergency forward jumpseats, fall back there if you need to"
  • Between the 2 barricades the player must defend, there's a black area which can be opened by shooting at it from the right, which will reveal a loot drop and a medkit.




Zombie Assault 4 (SAS4) Mission 1 - Onslaught

A level 39 player's walk through of Onslaught.

  • At low levels, try double-blocking both entrances with boxes because it's very likely that the barricades will fall. To preserve the barriers integrity while still having boxes try and use any sentry turrets to hold off the zombies, giving you enough time to push boxes together agaisnt the barriers. When the boss comes, fall back to the center area and move around the boxes, making the boss chase you in a circle. If there are too many weaker zombies, shoot the explosive barrels to kill them. Fall back to the forward jump seats if you need to. If the tall, darker boxes in the center room ever get in the way of you shooting the boss, you can shoot them to destroy them, since they'll just get in the way.
  • When the pilot drops several loots, it's not recommended to pick them all, because again, zombies can ruin the barricades easily while you picking them. To avoid


  • Unlike singleplayer, where you work alone to strategize, you will have to cooperate with multiple people to achieve victory.
  • When either of the ramp doors fall, do not rush to the center stash between the ramp doors alone. Have your team coordinate when to break into that stash as a single player will most likely get overrun by the stepped up zombies.
  • Similar to singleplayer, an effective start is to block both ramp doors but a faster, more supply consuming tactic is for all players except one to block the door with crates while turrets and the remaining player defend them.
  • At higher levels, it is simple for players to split into two teams, one in charge of each door and entirely prevent zombies from reaching the doors. So long as reloads are spaced decently well, zombies can be prevented from damaging the door altogether. When the boss comes, it will quickly destroy even full health doors however and a tactic of running around the ship is fast and cheap on ammo.

Map Specific Achievements


Very first frames show it sliding

  • Notice that the whole map looks like the evac dropship from mission Vaccine.
  • The first frames of the barricades' breaking animation may suggest they were intended to slide open, rather than break down.
  • The dropship doesn't actually move at the end, but rather a camera shake effect is just added. Oddly, the same thing happens when the ramps are repaired, as they don't close.
  • On the first playthrough (that is, on level 1), the second-to-last message will appear at 0:43 (as stated above), but will still say "...nose up in one minute", despite the fact that the dropship will actually depart in 43 seconds, assuming the boss is dead by then. Even if not, it will usually take longer than the minute to beat the boss.
  • The mobile version's Onslaught map was altered as of version 1.4 for Android.
  • Also with update 1.4, it seems like the timer mark for mobile is screwed up. The side loots shows up around 1:30ish. The jump seats area will open around :43, rather than 1 minute. And the boss(es) will appear about :27.
  • In the mobile version, you can break open the 'secret' spot without zombies breaking the rear doors. In order to do this you will need a long weapon (eg: Shockfield). You can also destroy the sliding doors in the middle of the map.
    • The same is also possible with weapons like the Luftplatzen.
  • From the intro cutscene, the military shuttle Mantis-12 is located in Bay 10
  • From the design of the ship in the intro cutscene as well as the blueprints, there may be a total of 24 bays in the spaceport
SAS: Zombie Assault 4 Missions
Onslaught · Vaccine · Survivors · Zombie Pods · VIP · Power Out · Last Stand · Ice Station · Meltdown