The following section contains information from a previous version of StarCraft II which is no longer valid.
The nydus worm underwent several changes during development.
At one time allies could can enter another player's nydus network, but allied zerg networks could not be linked
The overseer could create a nydus worm after a nydus network had been produced as of October 2008. This ability cost energy.
The overseer lost the ability to make nydus worms as of March 2009.
In June 2008, the nydus worm was built directly from the nydus network, a point on the creep is selected (it could only emerge onto the creep) and the nydus worm erupted. By August 2009 it was produced from the network again.
The nydus worm used to be a mobile worm unit with two modes, "stationary" and "mobile". There was a delay when it shifted from one mode to another.
Blizzard planned on allowing players to produce different kinds of nydus worms. Examples include a worm that can spew creep across several screens to create a zerg assault highway as well and a worm that attacks only enemy buildings which are used as a ground based zerg base raider.
As of September 2012 these new versions have yet to appear, and were eventually canceled, though variant strain data does exist in the game's beta files.
↑1. No, Overseer does not have Nydus Worm spawning ability any more.
2. You can build Creep Tumor from the Queen only on the creep to expand it.
3. It just looks like other Zerg buildings while it is being summoned and the worm bursts out of the creep when the summoning is done. Hard to describe the animation of the popping up;;
4. Yes, units are coming out of the Nydus Worm/Nydus Network one-by-one and they come out in the same order they entered in. Cydra. 2009-03-2. Questions about Nydus mechanics (third post). Battle.net StarCraft II General Discussion Forum. Accessed 2009-03-02.
↑"When a nydus worm surfaces, and after releasing its troops, does it become a back and forth instant transport system similar to the nydus cannal in SC1? Or in other words, is it a 2 way road?"
"It is a 2 way transport, allowing units to both move in and out."
"After being deployed and releasing troops, is the nydus fixed forever in its spot, or can it move again?"
"The Nydus Worm can repack up and move again. To change the Nydus Worm from its stationary mode to mobile mode, there will be a delay, which will be subject to balance." Karune, SavioSeth. 2008-06-03. Karune Answers 8 Questions on Another Site. Battle.net StarCraft II General Discussion Forum. Accessed 2008-06-04.