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While user made missions would be great, unless you plan to have the system be very complex with control over broad aspects of the game, it likely won't see tons of traction and thus be less important. 
Basically, either go all in on user mission customisation and feature modability, or save such things for later.
That is my take at least.

If you do implement a voice/breathing etc. Then it would probably be a decent idea to control it with a separate audio slider in the settings, that way people can just 'fix' whatever issue they have instead of anything being a deal-breaker.

So if I'm understanding this correctly, then this game will be the first of its kind to have semi dynamic weather, nice.

Will the weather and wetness have any gameplay effects in the future, or will it be purely visual?

These progress updates fill me with hope for the future of ENF gaming.

btw, if you are having issues with pollen, I can wholeheartedly recommend an air purifier, even a cheap one blowing air in the general direction of your face during the night helps a ton with pollen. IKEA has some relatively cheap ones, with notably cheap particulate filters, like the FÖRNUFTIG, can recommend if you have the cash to spare.