From the in-game introduction
You must completely master the functions of the custom CS-05 and your assignment is to clear all the indicated zones under various conditions. Good luck!
In Metal Stoker, you pilot a hover tank and fight enemy tanks, turrets, and other hover vehicles. You acquire new weapons, both offensive and defensive, and can switch at any time. Each zone has multiple areas to clear, which can be a static screen, a small arena, or a large scrolling section.