The Nanite Factory produces nano-sized robots, which are considered the ultimate achievement in robotic technology. These are capable of greatly increasing construction speed of buildings, defenses and ships. In game terms, nanites cut in half the construction time for all buildings, ships, and defense cumulatively for every level that is upgraded. Thus it is the only building which always takes the same time to upgrade (assuming you don’t change your robotics factory level above the level 10 prerequisite for nanite).
Particularly useful when building ships and defensive structures (because construction time for ships and defenses never increases), each level of the Nanite Factory cuts their build times in half compared to the previous level.
For example: A ship that would take 1 hour to build would be decreased to 30 minutes with one level of nanite, 15 minutes with another nanite level, and only 7.5 minutes build time with a third nanite level. High nanite levels eventually result in the ability to “insta-build” ships and defenses (when their production time reaches zero seconds). The ability to instantly create large numbers of ships or defensive structures (if you have the resources to pay for them) provides a fantastic tactical advantage. Meanwhile, the cost of the Nanite Factory itself doubles with every level.
The advantage nanites provide when building mines remains constant. As the building time of a mine doubles every level, each level of nanite cuts construction time in half. Increasing nanite levels are thus essential to developing high mine levels.