Download SAS: Zombie Assault 4 APK 2.2.2 Free for Android

Nightmarish Savage Necrosis Elites in SAS: Zombie Assault 4 carry 10x health, 10x damage, and 75% resistance to every damage type, and they only spawn when four level-99 players queue together.

SAS: Zombie Assault 4 is a top-down twin-stick zombie shooter with RPG-style progression from Ninja Kiwi, the studio behind Bloons TD, with version 2.2.2 live on Android. The story sits in the year 3104, when a virus outbreak on the trans-federation planet of Thera turns humanity’s past horrors loose on the present. You play a special-forces soldier across single-player missions and 4-player online co-op, picking one of three classes, building a 19-point skill tree, and pulling 160+ guns and armor pieces from strongboxes. Weapons climb through normal, RED, and BLACK grades, and the endgame revolves around Nightmare Mode and rotating events that drop the rarest loot in the game.

Assault, Medic, and Heavy: three classes with 19-skill trees

The class you pick decides your base health and your level-20 ultimate, and those two things shape every build that follows. Assault starts with 2,000 health and gains 100 per level, Heavy starts highest at 2,200 (also +100 per level), and Medic trades raw bulk for healing and crowd control. Every class shares the same starting sidearm, the HVM 001, but the primary differs: Assault opens with the Z-1 Assault, Heavy with the Z-5 Heavy, and Medic with the shock-element CM Gigavolt.

Each class has 7 special skills layered over a shared base tree, and the level-20 ultimate is the dividing line between them:

• Assault (Assault Team): drops a squad of NPC soldiers wielding HVM 005, HVM 004, and HVM MPG rifles for a few seconds. Most endgame builds spend one point here to use them as bullet-sponge dummies, then pour points into Adrenaline (boosts move speed, fire rate, and reload) and Critical Shot, often maxed at 25 each.
• Medic (Zombie Antidote): deals heavy area damage to zombies. Combat Medics skip it past level 60 because it does little to bosses in Nightmare, and instead invest in Bio Cleanse, which slows normal zombies to a crawl with poison.
• Heavy (Aerial Bombardment): calls an airstrike on a chosen area, but it uses the most energy and the longest cooldown of any class ultimate. Heavy’s real value is Hold the Line, which raises weapon damage and penetration while standing still, plus Tough Body and Toughness for stacking damage reduction.

You begin with two character slots and 5,000 SAS cash. A third slot unlocks when a character hits level 20, a fourth at level 60, and the fifth and sixth cost 20 NK Coins each. Because skills can be respecced, the smart move early is testing builds rather than committing, since wasted points in Health Regen or Energy Boost are the most common beginner trap.

Over 160 guns sit locked inside tiered strongboxes

You never buy weapons in SAS 4, you gamble for them, and the box tier decides your odds. Strongboxes drop on level-up, from secret rooms, and off dead enemies, climbing through Neodymium, Molybdenum, Promethium, Thulium, and the rare Nantonium and Black tiers. A RED-grade weapon roughly doubles the firepower of its normal version, and BLACK gear sits above that, so the same gun can swing wildly in power depending on the grade you pull.

Your loadout holds a pistol sidearm and up to two primaries, drawn from these weapon classes:

• Submachine guns and assault rifles: high fire rate for clearing standard zombie packs. The RIA 20 Striker is a common Assault starter pull, while shock-element autos like the CM Gigavolt shine against grouped targets.
• Shotguns and machine guns (LMGs): the CM 505 Alpha and HVM 008 trade range for stopping power, suiting Heavy builds that hold a chokepoint.
• Flamethrowers, rocket launchers, and lightning guns: the Ronson WP Flamethrower applies fire damage over time, useful against high-resist Nightmare enemies that shrug off direct hits.
• Premium and championship weapons: the Contagion (a $9.99 premium LMG added in update 1.9) and the CM X-1 Furie sit outside the normal loot pool entirely.

On top of grades, you slot augmentations that raise damage, rate of fire, reload speed, resistance, or healing. One augment most guides miss is Adaptive, which counters the Nightmarish modifier and quietly eases normal runs too, which is why veteran players rank it above Biosynthesis.

The zombie roster runs from Spitters to Nightmarish bosses

SAS 4 enemies are not a flat horde, they scale through modifiers and elite variants that change how you have to fight them. Standard zombies rush in melee, Spitters fire ranged poison from a distance, Bloaters explode chemical damage on death, and the gun-toting Scavengers (added with the Montano car level) shoot back. Z-Droid variants like Zombdroid Servants and Soldiers add another layer, and on mobile both can spawn with the Nightmarish modifier.

Past the rank-and-file sit the bosses: Necrosis, Devastator, and the Savage Mech among them. Each level closes on a boss, and Nightmare adds a second one mid-mission, with the boss type scaled to roughly double the total player levels in the lobby. Regular zombies can roll a long list of elite modifiers (Extra Strong, Extra Fast, Dark Minion, Berserk, Regenerating, Acid Blood, and more), but bosses are capped at four: Extra Strong, Extra Fast, Dark Minion, and Berserk.

The Nightmarish modifier is the spike that breaks unprepared builds. It grants 10x health, 10x damage, and 1.5x size (which extends attack range by 50%), plus 75% resistance to all damage types and a 5% armor-penetration on top. This is exactly why Cryo grenades and Ronson Cryogenic turrets matter at the top level, since freezing a Nightmarish boss for a few seconds is often the only window you get to reposition or burn it down.

How Nightmare Mode at level 35 reshapes the endgame

Nightmare Mode unlocks at level 35, but jumping in that early is a mistake, because bosses scale to your level and weak bosses drop fewer boxes and less cash. It is a multiplayer-only mode (introduced in update 1.6) that costs one ticket per match, with five tickets refreshing daily. Every map is individually redesigned, zombies hit far harder, and Nantonium boxes carry a chance to drop Black Keys and Elite Augment Cores, the latter only from Savage Devastator or Savage Necrosis Elites.

The reward structure ties straight to leaderboard ranking in event-style Nightmare modes. Last Man Standing, for example, pays out by percentile: Bronze covers the top 75%, climbing through Silver, Gold, and Platinum up to Diamond at the top 1%, which hands out 4 Nantonium Boxes, 5 Promethium Boxes, and 20 SAS Cred Packs. That gap between Bronze and Diamond is the entire reason high-level squads grind Nightmare instead of standard Quick Match, since the box quality at the top tiers is where BLACK gear actually becomes realistic.

Seven story missions, 4-player co-op, and rotating events

The whole campaign and every event run solo or with up to three other players, and the mode you pick changes the objective, not just the difficulty. Beyond the story missions on planets like Thera and Montano, the live service rotates a steady set of event types, each with its own rules:

• Apocalypse and Last Man Standing: survival and last-soldier-standing brawls where, from wave 30, zombies start ignoring 5% of your armor damage reduction, climbing 5% every five waves up to 25%.
• Virus Samples: kill zombies and collect the samples they drop, then outscore other players for ranked rewards.
• Faction War (Power Out and Boss Hunt): Power Out tasks you with keeping emergency generators online while zombies smash them, and Necrosis bosses can spawn in the Boss Hunt variant.
• Zombie Bounties: passive events that track a specific zombie type (like Spitters) across your Quick Match games, with the kill only counting if you land it yourself.

Power-ups bought before a mission matter more than most new players realize. Tank cuts incoming damage and makes healing more effective, and it also hands you Cryo grenades, which is why experienced players pick it over High Roller, since High Roller never actually guarantees better box quality or quantity.

What’s new in the version 2.2.2 update

The current build, version 2.2.2, continues the balance and event tuning Ninja Kiwi has rolled out across recent patches. The headline content addition is the Montano level: a new map where you take the wheel of brand-new cars and fight through abandoned streets against zombie hordes and the gun-toting Scavenger enemies. Recent changes documented in the changelog include:

• Boss damage fix: a bug that reduced direct damage to bosses by 50% was patched, so hitscan and direct-hit weapons now deal full damage to bosses, while damage-over-time guns like the Stripper and Krakatoa were never affected.
• VIP Nightmare: can now spawn a full boss at the end of the run instead of another mid-boss, and a freeze affecting high-level groups was fixed.
• AoE crit fix: rockets and other area weapons that previously could not land critical hits can now crit again.
• Faction War armor bonus: weapons with very small clip sizes now gain a minimum of 1 extra clip from the new Faction War armor bonus, and Necrosis bosses returned to Faction War Boss Hunt games.
• Event scaling: Power Out zombie spawn timing is faster, and event armor-penetration scaling was added at higher waves.

SAS: Zombie Assault 4 MOD APK features

This MOD removes the two biggest grind walls in SAS 4, the strongbox loot gamble and the SAS-cash economy, so you can build a maxed Assault, Medic, or Heavy without farming Nightmare for weeks. It targets players who want to test top-tier loadouts, push deep into Nightmare and event modes, and reach level 100 content without the random box drops standing in the way.

Unlimited Money (SAS Cash)

SAS cash stays maxed instead of starting at the usual 5,000 and forcing you to ration it across augments, turrets, and grenades. You can fully augment a RED-grade gun with Adaptive and damage cores from the first character, then stock Cryo grenades and Ronson Cryogenic turrets for Nightmare runs without saving up. This matters most around level 35, the Nightmare unlock, where the stock game expects hours of Quick Match farming before you can afford a survivable kit against Necrosis bosses.

Unlimited Skill Points

Every node in the 19-skill tree opens at once, so you skip the slow per-level point drip the stock version ties to leveling. You can run Adrenaline 25 and Critical Shot 25 on Assault, max Hold the Line and Tough Body on Heavy, and still keep the level-20 ultimate, instead of choosing between damage and survival. This removes the respec tax entirely, which in the stock game is the main reason new players stall when they sink points into weak skills like Bad Blood or Health Regen.

All Premium Weapons and Strongboxes Unlocked

The premium and championship guns locked behind real money or rare boxes are available from the start, including the Contagion LMG (normally $9.99) and the CM X-1 Furie. You also bypass the strongbox tier gamble, so RED and BLACK grades of guns like the CM 505 Alpha or RIA 20 Striker are accessible without grinding Nantonium boxes from Diamond-tier Nightmare finishes. In the stock game, pulling a single BLACK weapon can take dozens of top-tier box drops.

God Mode (Unlimited Health)

Your health does not drop, which neutralizes the Nightmarish modifier’s 10x damage and the 75% resist bosses that normally one-shot under-geared players. You can stand in a Spitter’s poison or tank a Savage Devastator while clearing a Power Out generator defense, something even a 2,200-HP Heavy with Tough Body struggles with at high Nightmare levels. It is most useful for solo-clearing event modes like Apocalypse past wave 30, where armor-penetration scaling makes survival builds increasingly thin.

The table below lays out the core differences between the stock SAS: Zombie Assault 4 and the MOD build, so you can see exactly which grind walls the MOD removes before downloading.

Frequently asked questions

Is the SAS: Zombie Assault 4 MOD APK safe to use?

The MOD is a modified package, so install it on a secondary Google account rather than your main one. SAS 4 has a long history of anti-cheat patches (NK has repeatedly nerfed exploit farms like the old savage Z-Droid box drops), so treat any modded build as carry-risk for online features and back up your data first.

Will the MOD get my account banned?

Online modes (Quick Match, Nightmare, Faction War) run server-side checks, so modded values like unlimited cash or God Mode can flag accounts in multiplayer. The safer approach is using the MOD for single-player missions and skill-tree testing, not for competing on event leaderboards where rewards scale by ranking.

How is the MOD different from the stock APK?

The stock APK gates guns behind random strongboxes and ties skills to slow leveling, while the MOD unlocks the 19-skill tree, all weapon grades, premium guns like the Contagion, and adds God Mode. The core gameplay, classes, and Nightmare structure stay identical, only the grind and survival walls are removed.

Can SAS: Zombie Assault 4 be played offline?

Yes, single-player missions run fully offline, and playing offline also disables the occasional ads. The catch is that Nightmare Mode, co-op Quick Match, and most ranked events require a connection, since they rely on matchmaking and server-side reward tracking.

What level do you need to reach Nightmare Mode?

Nightmare unlocks at character level 35, and the requirement is per-character, so a high-level alt cannot bypass it. Even so, jumping in at 35 is discouraged, because bosses scale to your level and drop fewer boxes and less cash when you are under-geared, making mid-40s with a RED weapon a more practical entry point.