Tomorrow the Iconians will be introduced in Galactic Civilizations II: Twilight of the Arnor Btea 3.

In the creation of the Galactic Civilizations universe (when it was just a series of unpublished stories), the Iconians were one of the first named civilizations.  A race of beings who were nearly wiped out of existence by their malevolent creations, the Yor.  Even in Galactic Civilizations I, the home world of the Yor was known as Iconia (even though the Iconians were not in that game).

The Yor used a biological plague to destroy the Iconian civilization. In the stories, the Terran Alliance discovers the Yor and Iconians quite by accident when humans begin dying from an unknown disease after discovering the Iconians.  This leads the humans far across the galaxy to discover the Yor in an effort to find a cure for the disease before mankind is wiped out.

The Iconian civilization is the only civilization that existed during the noontide of the Precursors. Before the Precursor civil war, which saw that civilization break into two factions now known as the Arnor and the Dread Lords, the Iconians were the servants of the Precursors.

In time, the Precursor war saw the Iconians as unwitting pawns in their struggle. The Precursor civilization resulted in the near extinction of the Iconian race. However, the Iconians have far more knowledge of the Precursors than any others.

Unfortunately, Iconian culture has not lent itself to technological research. Economics, industry, and research as we know them to be are completely foreign to the Iconians. The Iconians replicated the Precursor way of life in all its forms. The Precursors, however, were potent because of their innate being. That is, the source of Precursor power was inherent. By contrast, the Iconians are a biological organism that evolved over millions of years on Iconia. As a result, the Iconians were always little more than a pale reflection of their masters.

The challenge of the Iconians is to develop a modern economic, cultural, and manufacturing civilization. To jump start this the Iconians have access to a great number of partially translated works of the Precursors to call upon.

The Iconians have many many unique technologies, improvements, and ships because frankly, the Iconians are a very unusual civilization.  They have, for instance, access to many Precursor technologies in watered down form.  They also have their own robotic technology:

The Iconians, in their quest to have servants of their own, constructed ever more advanced machines to labor for them. Just as the Iconians were servants of the Precursors, so to did these near-sentient machines act as servants to the Iconians.

During the civil war between the Precursors, the faction known today as the Dread Lords modified the robotic servants of the Iconians to achieve sentience. Thus was born the malevolent race known as the Yor. The Yor quickly sought to exterminate their creators. They did so first using a biological plague since, at first, the Iconians vastly outnumbered the Yor. With the population of the Iconians decimated, the Yor then set upon the scattered survivors methodically in an effort to wipe out the remaining grops.

With some help from the Arnor, the Iconians escaped to a distant world now known as "New Iconia". To this day, Iconia is inhabited by the Yor.

While the Iconians lost much of their technology, so skilled were they in the construction of robots that this is an area that the Iconians continue to lead. Of course, they are very careful now to construct their servants such that they are no where near what could be considered sentient.

The core of the Iconian strategy is thusly: They are not as good at weapons as other civilizations. But their ships are incredibly tough thanks to access to self-healing armor, organic hull technologies, etc.