Sounds interesting, nice background story too, I particularly like the reasoning behind why mecha have become a more viable form of transport. I also like that the mecha are slow ponderous machines, this makes the setting feeling more gritty and believable with none of the 'techno-sheek' of the mecha you see in manga films. Why no frikkin' laser beams?
PS since I've been doing a few campaign logos for people recently would you like me to do one for Viral Earth?
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~The ravings of a single mad Goblin is bad enough, but such a power-hungry, malice-filled creature as Mortis can never hope to be understood~