A vector is a carrier of a disease Ex.( A mosquito is a vector the the disease Malaria.) You might see where I'm going with this ;)
I was thinking you could add bugs and disease.
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Ideas:
<Insect Plague: Locust descend on your crops once every 365 days and stay until every plant on the map is gone.
>Prevention: Research pesticide to spray on your crops. (Pesticide will need to be crafted or purchased via trader.)
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<Disease Plague: An unknown disease will spread through your colony rendering it undefended and production less (Depending on the severity of course) there could be all kinds of disease like The Black Death, Spanish Flu, Measles, and even Necrosis (I think that's the technical term for a zombie disease XD)
>Prevention: Build massive walls around your colony (So that infected raiders and passers bys can't easily get to your colonist)
Pesticides can ward off disease carrying vectors and keep you safe.
~Solution: If you do get sick colonist you would have to do research to find the vector (or passer by/Raider that caused the plague) and then develop a cure. If a cure is inevitably too costy or time consuming, execution is always an option ;)
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<Problem: With the wood that's coming in alpha 3 (or 4 I can't remember) it's bound to draw in termites so you'll have to treat your wood or it will rot and break or collapse.
>Solution: Either you can treat your wood or the higher level the builder that builds the wood makes the items less susceptible to the termites.
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Well that's all I could think of thanks for reading ;)