Echelon are gone.
The Virus:
The virus is a 100% biological race. Now, your thinking, "Wow, another zerg! Just what we need..." No, its not another zerg. This race is made of intelligent bacteria, and infects all living things, converting them into their own. The Virus is capable of infecting any unit from another race. Because the virus is too small to form its own combat units, it relies on infecting Arcane and Human things. The Virus also has a small arsenal of ancient, derelict technology.
Backstory:
2636, 8 months into the Human-Arcane war.
An EAA fleet consisting of 4 Beam Frigates, and 2 Destroyers had left Earth for their outpost on the Moon. 10 hours after launch, an object was detected on their scanners. 3 salvage units were launched, and brought the object back to the lead destroyer. The object was shaped like a triangle, with an odd, reddish glow on its outer layer. Though, that was all that they ever got to learn about the thing, for about one minute after they brought the object in, everyone in the hanger bay became infected.
The object began transmitting a signal, just as everyone in the hanger bay rushed into other sections of the ship. In a matter of minutes, 90% of the crew was infected, just leaving the Bridge left. Just as the Captain was about to initiate self destruct, all the power in the ship went down; life support on the bridge was gone, and so were the lives of the people there.
The infected destroyer started launching its infected missiles to the rest of the EAA fleet. Through these missiles, the rest of the fleet did too, become infected. The fleet was never seen, or heard from again.
In 2637, Arcane sensors picked up several objects inbound, coming in to the atmosphere extremely fast. Thousands of the things hit Earth everywhere. Because nobody knew what happened to the EAA fleet, nobody knew about the Virus. Outbreaks were everywhere, consuming every living thing it could infect. After 3 days, the Virus had an army of unbelievable size. They marched outward, on a crusade to destroy or assimilate all life.
By the way, the reddish stuff is the bacteria itself.
Crashed Derelict Asteroid Harverter
(Not final, just sorta the look I want for the Virus HQ)