Natural Selection Wiki
Natural Selection Wiki
"Getting the job done & saving lives!"
TSA Frontiersmen
Team Resources
Marines res 3
Icon marine supply 15 / 200
Move Speed: 2, 0.8 (in combat)
Infestation Speed: 0.8
Build Time: 7 seconds
Builds From: Robotics Factory
Purchase By: Marine Commander


The Mobile Automated Constructor (MAC) is a robot that can build structures and repair armor. It can be built from the Robotics Factory for 3 Tres.

The MAC provides no Line of Sight for the Marine Team.

MACs weld at:

  • 50 hp per second for buildings (base weld rate)
  • 25 armor per second for players or exos while not in combat (base weld rate * 0.5)
  • 5 armor per second for players or exos while in combat (base weld rate * 0.1)


Since MACs do not have vision themselves, they cannot be used to spot enemies other than be being attacked. They are mostly used to weld up bases or Extractors far away from the frontlines. They are most common in the later stages of the game, when map presence is firmly established and most major investments in tech have been made, so the economic downside of losing a MAC or two to Aliens within the own territory is not as severe as it would be while saving up for those investments.
MACs can also be used to build sneaky Phase Gates on the other side of the Map during engagements, without having to divert any Marines from those engagements. Those gates can then be used to quickly switch sides and attack an unprotected Hive while Alien Lifeforms are out of position. This works especially well in conjunction with Power Surge since it takes MACs quite long to build both the Phase Gate and Power Node.
There is a Mod available, which has to be run on a Server, that allows MACs to pick up and relocate certain Buildings to make MACs more useful, since they are rarely used in 10 vs. 10 matches.