A Zeus is an elite humanoid sniper. It is the result of an experiment to create a supersoldier who could wield the C7 Energy Rifle. The triple cylinder C7 promised unparalleled power, rate of fire, and effective range, but no soldier had the strength to carry it, let alone aim it.
A Zeus trains for 10 years, after which it is given a stealth-green gamma suit, which uses nanotechnology to boost physical strength, and a powered visor to augment eyesight.
Even still, a Zeus can only use the C7 at its lowest-power setting. But as Zeuses have proved time and again, that is enough to unleash devastation in battle from afar.