Attack of the Earthlings combines turn-based combat and stealth in a dark comedic single player campaign, where you take control of the native alien race to defend your home world from the invading humans. You control the Swarmers, a highly aggressive insectoid species, who must kill and consume humans in order to expand your army to repel the Galactoil Corporation from your homeworld. As you gain more biomass (the fleshy currency converted from eating humans), your grunts can be transformed into new more specialised units units with different roles and unique abilities. You must sneak, kill and consume your way up the 7 levels of the Galactoil Drill thwarting the plans set in place by the game’s two main antagonists - PA Pecker and RM Dickinham.