The very first thing you notice about mechagon is the trees. Choking out all other plant life, the Ketsu tree is a volatile, poisonous, rampantly successful and hardy life form, whose leaves are coated in a fine dust of toxins, protecting it as it grows and killing all life that wanders by, replenishing the soil as they decompose.
The bark of the ketsu is extremely valuable once processed, being an extremely hard material that somehow manages to maintain its flexibility. The gnomes of Mechagon have built an entire society on this fact, and their factories and cities are built into a criss-crossing network of underground tunnels, allowing them to avoid the toxic dust of the Ketsu tree while using its roots as a food source, and digging deep underground for water.
The famed mechagon exploration teams are bands of fighters and adventurers that venture out of the safety of the city to harvest the valuable bark of the ketsu tree. Clad in goggles, strange suits, and armed and armored with the latest wild invention of the inquisitive gnomish engineers, they brave the dangers of the forest and harvest the bark that fuels their society.
The factories of mechagon, most notably the underground mega-complex of Mechagon City labor day in and day out to process the raw ketsu bark brought down from the surface by the exploration teams, their large smokestacks poking out of the forest floor and pumping black coal smoke over the treeline of the nation.