Note: I think the most important improvements are related to interface, (And why is mouse interactivity so small? I've wondered this for a while) but that being said;
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Stage I.)
Now that blood details are being implemented, as well as more specific and small wounds as well as scarring, would it be appropriate for mosquitoes and gnats to be introduced into the game?
Infestations of the creatures could grow in shallow, stagnant water, and they could menace dwarves, bringing negative thoughts and creating small pricks and damages toward dwarves as they suck their blood.
Particularly large swarms could overwhelm dwarves with bites.
Stage II)
Not just bites, but infections could be passed between dwarves. After the venom arc is finished, and disease is begun, a diseased dwarf or creature whose blood is drank by one mosquito can then pass that disease onto another dwarf after the mosquito drinks the blood of the subsequent dwarf.
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However, I wonder how the mosquitoes would not clutter the game- since they are by their nature, very small and numerous could they only be represented in "swarm" factor? Perhaps that would be best- to have wandering mosquito swarms hunted by dwarf "exterminators" who have to kill them with poisonous sulphur gas, magma, etc.