“ The members of the party has unknowingly been infected by a mysterious plague and have been spreading the virus for quite some time now while adventuring. They start to hear rumors of all the cities in quarantine after they travelled trough. Will they discover the source of this? Will people start to avoid them, try to kill them?”
“ After the PCs defeat (or force the rapid retreat of) a villanous necromancer/demon summoner, they discover a book. This book outlines how to summon a demon whose power increases according to the size of the summoning circle used to summon it. And after the PCs examine a map of the country, they find that the layout of the cities and roads match up with the required summoning circle. In fact, the final road that would complete the circle is currently in construction.
With anyone who can find out about the circle and the ritual to summon the demon able to somehow make the final road/line, and destruction of the cities and roads currently in existence out of the question (unless this is an evil campaign- that removes the moral quandary), how are the PCs going to solve this problem?”
“ Giant mushrooms the size of trees. The stems and parts of the caps can be used in construction, and only the gills are soft enough to eat. An entire fungi-forest can grow in a matter of days, provided the correct conditions. Most fungus trees last about a month before collapsing, but not before a new generation sprouts to provide shade for the next spores.”