M.A.S.S. Builder is a dynamic action-slasher about combat robots with a third-person view and role-playing elements in a sci-fi setting. After the appearance of unknown beasts of the void, most of humanity practically disappeared from the face of the Earth. A war for survival has broken out across the world, turning land and settlements into war zones. The few survivors were forced to move into equipped bunkers to invent new military technology based on M.A.S.S. In the game you have to control deadly combat robots and fight hordes of opponents who want to completely exterminate all people.