Nydus worm

The nydus worm is a zerg transport strain. Each nydus worm acts as an opening in a system of tunnels created by the nydus network.

The nydus worm was first observed as early as late 2502 on Urona Sigma by terran forces.

Game Structure
The nydus worm can spawn anywhere the player can see.

The nydus worm grants a player access to a "nydus system" through the UI, which connects all nydus worm and networks. Units that enter either a worm or network become "lost" within this network, and cannot be targeted or harmed by enemy forces.

Air units and mobile crawlers cannot enter the system.

The nydus worm can be used to transport as many units as are selectable (up to 255 in the current build). These units are visible within the system. However, only the first several units inside can be seen. Units exit one-by-one in the order they entered.

Each worm can be given a rally point. Units which exit that particular worm automatically attack-move to that point.

The system persists unless all networks and worms are destroyed, in which case all units being transported will be lost.

Allies cannot share nydus networks but can enter another player's nydus network.

Strategies
Nydus worms can quickly transport units between multiple zerg bases, in a manner similar to nydus canals.

Using multiple nydus worms to transport units into an enemy base quickly is suggested, as nydus worms can be quickly killed due to their low hit points. A zerg player can unleash nydus worms near multiple enemy bases, then choose to send zerg only against the base the enemy does not reinforce (in effect, tricking their opponent).

The player must see the area the nydus worm will be spawned at. They can use changelings or burrowed infestors to do so. Air units such as overseers make good spotters as well.

A zerg player loads their units into a nydus network and unloads them at the same nydus network or at any nydus worm they have built. The worm can be used to quickly move some drones over to a newly built expansion. It may also prove useful to build the nydus network close to the drones, in case of enemy raids.

Development
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.

The nydus worm was visible without a detector while transporting units underground and was capable of traversing gaps between space platforms.

It has since become a stationary structure.