There are alternate [b] magical [/b] universes that intersect with humanity it's not the same thing. There are of course alternate timelines and worlds, but trust me when I say alternate-dimension/timey-wimey nonsense would be a pretty big development and something reserved for later. Like Aliens. 

Villains hide. This is a giant robot where all he does is hunt superhumans. That's it. If they had somebody like that running around splattering civilian superhumans and causing massive collateral damage, the Government or the League would hate up and wreck the utter living shit out of it. This isn't the comics where villains can get away with having no subtlety. 

I could buy some kind of Terminator made by a mad scientist, who infiltrates society and bides his time but there is no way a rampaging giant-ass robot like Gigakill would stay in operation for more than a few months.