Summary:

Terrahold is a strategy sandbox about building and defending a colony on a living procedural planet. Starting with a teleporter and a single drone, the player explores the world, establishes resource outposts, expands a shared power grid, and develops the colony toward the energy output required to open a permanent tunnel home. The planet reacts to the colony's expansion through spreading alien vegetation, hostile creatures, eggs, spores, and other environmental threats rather than conventional scripted attack waves. Players can use autonomous robots, defensive structures, force fields, bridges, radar, and terraforming to reshape terrain, protect infrastructure, and expand into hostile territory.