So, you know how to write a professional GDD? As in, professional? There is a difference between a GDD and an idea.
Yes, i can write a GDD i will put all the details into the GDD and i will explain it as-if i am explaining it to a developer so they understand it better with percentages and other things
Another snipped of information from my GDD
SFX Volume, This would turn the sound effects down or up, this will start at a base of 50% and can be turned down to 0 which would be no sound at all and all the way up to 100% with 100% been the loudest it can go, as with the sensitivity if you drop it by 10% below 50% each time you drop it down it will get quieter if you slide it above 50% each time you go 10% higher after 50% it would get louder
This is how i am writing in my GDD, there will also be concept Art within there to help facilitate what i write.
Edit, here is what my GDD look's like, Terrible cropping skills, Clicky here