From the Introduction:
In 1898 the Martian Invasion came, struck down terrestrial armies, overwhelmed all of mankind, and then collapsed - destroyed apparently by the tiniest defenders. The Earth had won and had beaten back the alien menace. From the ruins, the great centers of industry and life shattered, humanity declared that victory had come. But perhaps it had not. Just as our own biosphere had offered a poison to the Martians in time, what they had brought to Earth offered an equally deadly toxin. The Red Weed did not simply vanish with the passing of the Invaders. It seemed briefly to pause and then it returned with a vengeance. What should have been a time of rebuilding became a brief respite before a longer and more insidious war began.
No one knows exactly when the Weed Swarm mutated, when it became some different. Rumors had come from the life-choked countryside, of small animals, insects, birds which had been changed - infected by tendrils from the plants. These crimson animals seemed crazed, rushing towards settlements only to be put down. It drips and drabs it began with a few, then a handful, then a pack off maddened animals. And then after seasons the Weed Swarms became smart - intelligently striking at targets. But even more dangerous were the hybrids and the fusions. Greater beats and monsters - grafted together out of red weed, animal flesh, scrap, and metal. The people of Earth fight a war against this roving menace - utilizing all of the industrial technology they can bring to bear.
And... some say... that is the problem.
There are rumors, dark rumors that the red Weed did not simply awaken itself. They say that experiments, delvings, researches by scientists and engineers across the planet created this threat. The Martians had died but left behind their technology, their organic science, their bodies, and their war machines. How could mankind resist the siren lure? How could they not adapt those techniques to make transports, steam conveyors, high-temperature furnaces, medical advancements, and, of course, weapons?
Great Britain still stands, overseen by her Majesty Queen Victoria. She has lost many of her colonies, but remains stronger and more intact than other besieged nations such as Austro-Hungary, The Ottoman Empire, and Czarist Russia. The British have led the way in the adaptation of Martian technologies, using those to fight back against the Weed Swarm and its many and varied minions. The newest secret weapon in the crown's arsenal are the mechanized armored suits or mecha, codenamed Steamlarks. Many hope that these will be the salvation of the Empire and the means for hunting down and destroying the Swarm's dens.
In Arclight Revelation Tianmar players take the role of teens recruited by The Crystal Palace to pilot Steamlarks. They will protect human civilization against the predations of the mutated remnants of the Martian Invasion of 1898. The Red Weed, once a simple symptom of the alien encroachment, has gained sentience, polluting and corrupting native flora and fauna. Weed Swarm now comes in many forms and monstrous shapes. To secretly raise and train pilots for the Steamlarks, The Crystal Palace has co-opted the Spencer House Academy. Those who possess the mental talent necessary to pilot the Steamlarks are brought to South London - one of several splintered enclaves made up from the once great city. The Divided by walls, the eleven London subdistricts are a mix of bordering holdings and towns separated by Weedlands.
The Crystal Palace operates in secret from the hidden Crystal Palace Development Fortress (CPDF). They need pilots with discipline, but also balance in their lives. Military-like living conditions and training resulted in catastrophe. Instead the staff have taken a more psychological approach - splitting pilot's lives between a public face of school-children as a secret existence of training and field operations. But even this is a strain on these young men and women - who must face the awful horror of the Weedswarm and still hope for normal lives. Can they survive?