Empires of the Undergrowth is an ant colony management game, in a fast-paced real-time strategy style. The player excavates their nest underground, constructing tunnels and chambers to store food and raise brood. On the surface, the ants claim territory, gather resources, overwhelm fearsome arachnids and clash with other colonies. Nest design, army size, composition and attack timing are key to securing victory.

Missions are narrated from the perspective of a documentary film maker studying the ants, who offers intelligent insight into the goings-on of the colony and the undergrowth beyond. The primary game mode in early access is Formicarium, where you take ownership of a home colony of unique DNA-harvesting ants as they work to assimilate the desirable traits of their foes. You can upgrade them by playing one-off missions, sometimes with your home colony and sometimes with other ant species.