Following a series of expeditions - some successful, others not - into the frigid Siberian tundra, corruption has spread from animals and people to a much larger threat. New heroes, better prepared than their predecessors, gather to face the prospect of a mechanical monster, but the changing landscape brings greater uncertainty as they explore Tunguska with fresh eyes.

The Gears of Corruption expansion to Expeditions adds elements of risk and danger in the form of secret bonuses on map tokens and a corrupted mech that roams the land. To counter these threats, the expansion offers 2 new mechs and 4 new character/companion pairs, as well as components for a 6th player. Gears of Corruption also accelerates early gameplay by giving players starting resources and a hero worker that can act as any type of worker.