The ZAC Assimilator is a unit which spawns ZAC fighters, one of the only player-allied fighters which fires missiles similar to those of the Zycon Storm. An unupgraded ZAC Assimilator spawns only one ZAC fighter. When upgraded, each base can spawn a maxiumum of 3, giving the player nine total. Any time a fighter is killed the base will spawn a new one after some time. Higher ranked ZAC Assimilators spawn fighters with better stats.
ZAC fighters deal fair damage, and draw considerable enemy fire. However due to the nature of ZAC fighter AI, they can cause problems for some bases:
-Fighters may clog and idle in one corner or direction of a map. They may be moved meticulously by hand to more preferable locations to fight in.
-Fighters tend to engage enemies outside of natural, unimproved ranges of most towers. If the ZAC fighters are unable to successfully eliminate enemies, enemies can simply pile up in large waves, and then advancing towards the players' base. Bases that do not have range boosts may be constantly unable to engage enemies skirmishing with ZAC fighters.
The X-ZAC Assimliator upgrade becomes available at Rank VII. The upgrade costs 2.000.000 gold. The upgrade gives the Assimilator as well as the Fighters a different model texture, offers +200 HP for the Assimilator and +50 HP for its fighters, damage increase for the ZAC fighters, and improved stun capabilities. Previous upgrades are kept through the upgrade.
- Dominance: Fighters start at rank 2-7 (6 levels)
- Turbo: +30%-165% attack power to fighters (10 levels)
- Final Armada: R1 + 1 fighter. RII +2 fighters (2 levels) [3 Fighters total]
- Mode Shift: Replaces Final Armada on an X-ZAC Assimilator. Provides different bonuses for the X-ZAC Assimilator. (Mobile Only)
Mode Shift is an upgrade that provides different bonuses for the Defensive Wall, and is exclusive to the mobile version of the game, replacing Terra Alloy. It also changes the colour of the Defensive Wall.
- Mode Shift I: X-ZAC Assimilator is white, and spawns normal X-ZAC fighters.
- Mode Shift II: X-ZAC Assimilator is blue, and spawns Tesla Fighters which can stun.
- Mode Shift III: X-ZAC Assimilator is green, and spawns ZAC Healers which heal friendly units.
- Mode Shift IV: X-ZAC Assimilator is orange, and spawns Tankers which have higher health than other fighters.
- Mode Shift V: X-ZAC Assimilator is purple, and spawns Nyon Fighters which can ghost enemies.
- Further upgrading Mode Shift will repeat the white-blue-green-orange-purple cycle.
- On the Flash version of the game, there is a glitch where if Oblivion is destroyed near a ZAC Fighter, a pair of Oblivion arms will appear on it. They are fully functional and will engage and inflict massive damage on enemies. The ZAC Fighter will continue to search for and attack enemies, and its normal weapons will remain functional. The arms will disappear if the ZAC Fighter is destroyed or if the level ends.
- On the Flash version of the game, there is another glitch which allows the player to have more than 3 ZAC Assimilators. The process can be repeated until the unit cap. This can be achieved by created ZAC Assimilators, then pressing the 'Z' key to create more ZAC Assimilators. This glitch will not be effected by the 3 ZAC Assimilator cap.
- On the mobile version of the game, a bug caused Tesla Fighters, ZAC Healers, Tankers and Nyon Fighters to not benefit from Dominance. Another bug also caused ZAC Assimilators to act as shielded units. These bugs were quickly fixed.