Here's the story:
"A lost empire is located in a rainforest on a planet in a foreign universe. The empire never invented the steam engine or use of fuel so everything they do is simply mechanic and relies on human or creature, much like elephants, power.
The civilization is split into a caste system. The upper caste, with engineers and priests, the lower caste with workers and soldiers. Their city is split into two rinks with the temple and science labs in the inner rink and workers and soldiers live in the outer rink. Most of the architecture, weapons and machines is built out of wood, with limited use of metal, stones, thatches and branches. They rely on complex and sophisticated wooden machines to construct buildings, harvest and seed crops or go to war.
However, due to an experiment in the science labs most of the inner rink and therefore most of the upper caste got wiped out. Without any political or intellectual leaders the Empire is at civil war. Only a select few know how to construct the machines and gangs of workers and soldiers fight for control of the inner rink.
Most of my inspiration comes from the Roman Empire or the Incas. Machines are inspired by bugs and insects.
Two pages of thumbnails for a wooden war machine. The second page explains a few of the mechanics."