Zero is the working title for a science-fiction/"real robot" series, idealized as "at least a graphic novel" in terms of visualization (i.e. not purely written.)
Taking place in the far future, the (working) title refers to a titular line of bipedal mechs used to resolve armed conflict. Standing at about 15 feet/5m upright, their main purpose is for all-purpose engagement - essentially, a metal "super-infantryman".
The advent of practical mechanical walkers as weapons changed the face of direct conventional warfare.
Yet, as the explosion of defensive technology making the mech viable was surpassed by offensive counter-innovations, the mech's evolution took on a drastic shift in tone. Its role on the field moved away from the gargantuan "walking super tanks" and toward designs emphasizing the mech's core strengths: versatility, maneuverability, and adaptability.
As development progressed and the function of the mech shifted to smaller, nimbler and more agile forms, two problems presented themselves: a growing concern for the now relatively larger target of a pilot's safety, and the need for a more efficient control scheme than the more archaic, traditional vehicular scheme.
I'm not quite sure as to the origins or reasons for the prevalence of bipedal mechs, assuming there is/will be any need to explain anyway. Salvaged/reverse-engineered alien technology is one somewhat far-out possibility (as I find it kinda interesting to gloss over something that sounds like it could be the subject of a full story to begin with) but that, implying it was a thwarted invasion, poses believability problems all its own and seems a bit ridiculous when paired with other stuff in the background/setting.
Having it simply be man-made is a thing but that would ask some thorough research of me, in regards to finding out how and why (hell, even if) it could be a practical, widespread idea.
Also undecided as to what exactly they'll be fighting.