Is a second wall a good idea for this design?

this and upstairs "gameroom" the existing framed wall has sheetrock on only one side and insulation on the back held in place by a netting material - this faces a large attic space. I could build a second wall with sheetrock on one side and still have only a 2 leaf design (if you ignore the attic and roof). I cannot do this on the angled portion or the ceiling and will only be adding a second layer of sheetrock. With this in mind should I build the second wall or just ad a second layer of sheetrock.

I've seen you post a couple times on this, so I'll TRY to help. IF you are not willing or able to to make a double frame (room in room) construction all the way around including the angle portion and or ceiling THEN just a 2x4 frame wall as shown in your pic will have some but not a lot of isolation gain... adding the 2x4 frame with 1 layer of sheetrock may not be worth the effort. Also worthy of mention and hope you already realize IF you wanted a double frame construction it seems like you are on a 2nd floor, most likely this would not be possible because of weight, you'd have to consult a structural engineer to find out how much weight you could add to the structure. Your other option just adding a layer of sheetrock to existing will also improve iso, not much, BUT may be the better option. Your attic space has 2 maybe 3 things to deal with, we'll call them outer leaf "walls" (one being the roof, the other the floor of attic (ceiling of another space?)) Presuming the attic space is triangular shaped then the seal of these other leaves has to be examined. It should be vented somehow? If it is vented you obviously DO NOT want to close these vents up for many reasons. Keeping all the above in mind, the best any of our members could do is make a wild guess as to how much iso improvement you'll get. Need to know how many holes are in attic space and it's leafs construction. My guess best thing for you is add layer of sheetrock with Green Glue (you mentioned this in other posts) all the way around room. Get in the attic and figure out if and how you can add mass to that outer leaf while maintaining your vent system. In the end it may not be worth it... you money might be better spent on another space. Hopefully you'll get another opinion and I hope (out of pride) I am correct with my above statements. Marc