The IronGait MK-6 is a bipedal heavy transport exoskeleton manufactured by Arcturus Defense Solutions, designed to carry personnel, equipment, or modular cargo frames across terrain that is impassable to wheeled or tracked vehicles — including the rubble fields, flooded sub-basements, collapsed highway sections, and active construction debris zones that characterize GLMZ's outer and contested districts. The platform stands 3.4 meters tall and is rated for 800 kg of payload beyond the operator's own mass. A single operator sits in a central torso cockpit with full limb-feedback servo controls; the Cinderblock AI co-pilot system handles dynamic balance, obstacle negotiation, and route optimization autonomously while the human operator manages navigation intent and cargo security. The MK-6's legs use a hydraulic-pneumatic hybrid actuation system with energy recovery at each footfall — partially supplemented by Ouroboros PiezoCore-derived ground-contact harvesting plates embedded in the foot pads.

Arcturus markets the MK-6 primarily to corporate security divisions, GLMZ's fragmented municipal enforcement bodies, and licensed private logistics contractors operating in red-zone terrain. A civilian freight variant — the IronGait MK-6C — strips the armored cab and weapons hardpoints in exchange for expanded cargo frame attachment points and a simplified Cinderblock AI interface. The MK-6C has found significant uptake among independent logistics operators in the outer districts as a means of moving goods through terrain where neither Kelpline's AquaSpine infrastructure nor standard road vehicles can operate. Both variants share a distinctive ground-shaking gait signature that residents of outer-ring districts have learned to read: a regular rhythmic impact means a contractor on a job; an irregular, accelerating cadence means something has gone wrong.