Primus

"Primus was always pretty nice. It was rivalling Earth for having the most econimical gains per year before the Fall. It's a shame now, the surface is covered in radioactive haze now, nothing grows there."

Overview
The third planet in the Alpha Centurai system, Primus was the first extrasolar world to be colonised by humans in 2114. It was noted as a prime candidate for colonisation due to having an earthlike  atmosphere and gravity. It started colonisation around the same time as Mars, though eventually overtook the nearer planet because of the more earthlike conditions. Before the Fall of The Imperium, its population consisted of roughly 15 billion inhabitants, though there is not a fraction of that number left.

Primus was designed from the ground-up for its cities to be as efficient as possible. The rooftops were all covered with solar panelling and faced north or south (Depending on position on the planet.), along with smart planning for efficient water usage and farming.

Primus Automated Manufacture was also the first company to be set up outside of Sol. A private funded group, PAM would mine out asteroids in-system for ores and invest primarily into building spaceraft for colonisation and interstellar travel between systems.

S'pher Assault
The S'pher did not take long to move onto Primus, being the closest colony to Earth. The first sightings of ships were at the same time as the attack on Mars, but the defence was a disaster like that of Earth. The UCE tried a different tactic, using nuclear weapons and orbital strikes on the ground attack force, filling the planet with lethal radiation and killing off much of the plant life. Like Mars and Exilion, the planet would be reduced to lifeless wasteland.

ADDITION 21/9/2703; Research by Intelligence Assets indicate native flaura and fauna are making a startling comeback, and their unusual resistance to sudden increases of radiation is currently undergoing research by UCE GEN-EN units in Exodus