The concept for the Gaudr race inside Homeworld2 game universe goes like this:
The Vaygr were able to align a myriad of worlds to support their war machine. By the time they've reached Hiigara, Makaan was lost in its own delusions of power and those loyals to him were the fast-frontline of the Vaygr. In the other hand, those that made sense that adventure wouldn't go too far stepped back even before the attack of Tanis and was waiting the outcome of the war.
Now this is the situation: Hiigarans are hunting the loyals to Makaan in their retreating process; the bulk of the Vaygr rear regrouped somewhere faraway and will not have a direct struggle against the Hiigarans forces and vice-versa. But they will be busy making their own cleaning. Other Vaygr forces are disbanded by their own. They were part of the corruption inside the Vaygr forces, now they are "for sale", but still a military group.
In the middle of this turmoil, there are plenty of races trying to find their way home now that the "deal" is over. One of these races are the Gaudr, as they are called by the Vaygr. They used to be specialized in strike and corvette forces, although having to use the Vaygr material. Since it wasn't an easy task, most of the Gaudr were working in logistical support, frigates and carriers in paralel of having a few squadrons. They are now regrouping themselves in a small flotilla to go back to Ylan, their homeworld.
Rumours says they have sensitive information, collected inside the Vaygr war machine. Hiigaran fleet inteligence wants to know what and to what extent they know, so a task force was dispatched to pursuit and maybe destroy them. The Vaygr Rear Forces will exploit this as an opportunity and wants to capture a few of them and destroy the rest. The remnants of the Vaygr Guard Forces sees them as real traitors - they were accounted for leaks and part of failure in the Siege.
Due to the disruption of the Vaygr, is not certain where the Gaudr homeworld planet is located. They are aware they can't go home directly and easily, but they seem to be going somewhere.
Where are the Gaudr going and what information do they hold? You and apparently half of a galaxy wants to know ... ; ]