With over 18 weapons to be bought and 18 other powers that includes and not limited to air strikes, armageddon and even an AI turret. Major Masher's goal is to collect soul capsules and assimilate them whilst attacking waves of enemies.
The game isn't story focussed. Your objective is to collect capsules that spawn at various spawn sites (called tabernacles/black boxes) and return to the assimilation point for assimilation.