For example, let's take the category Earth/Plants/Healing/Ores/Gems: It can be done in many ways and concentrated on 1 or more part.
If done in the Medieval style, it could be discovering what kind of plants are poisonous and what are beneficial to mankind [b]OR if in the Jurassic Age,[/b] it could be about escaping carnivorous plants [b]/or/and [/b] finding dragons that could hunt for ores or gems.
Get the idea what I mean when I say it can be done in different ways or in different themes?