This mod is set in the era of  "Star Wars Episode III", containing just the wars between the stormtroopers, and battledroids clones (clones were of the "Old Republic" that did not go to the Empire) ...
The "hydra" of the army (stormtroopers) is the "X-Wing" (Rebels Vehicle) because, as happens in so far as the clones become stormtroopers, the Empire still uses some vehicles of the Republic. Not yet had much time to design all the vehicles.

The "X-Wing" is a ship that is the Rebel faction, but the design came from the Republic ship "ARC-170 Clone Fighter."