Game bags sounds pretty much like common sense. Most hunters will take these afield, especially elk hunters, to pack their animal or quarters for transport home. However, most hunters also take the cheap cheesecloth type bags that are good for only a single use.
Cheesecloth bags work great to keep the bugs and flies off of your carcass, but they do little to keep small bugs, like ants, off of your meat--the cloth is too porous to prevent these smaller critters from helping themselves. And if you're camped by a busy dirt road, your meat gets a nice coating of dust after only a single day while hanging in camp. And then don't forget the drive home with the meat in the back of the truck. Cheesecloth does little to keep most of the dust off the meat.
If you spend about twice as much (it's about $4 for a cheesecloth bag) you can get much higher quality game bags that remind me more of stretchy t-shirt material than cheesecloth. These bags hiave a much finer mesh to them as well--they keep out the smaller bugs and also work well as a dust barrier. They are also much stronger material than the cheescloth and don't easily tear. We generally find them at Wal-mart in a 4 pack, each bag the perfect size for a quarter of elk. However, the best feature of these higher quality bags is they are re-usable. Once home, I simply rinse them out with a hose and then run them through the laundry. They come out looking like new.
We have a set of these bags that have been used 5-6 times and they still don't show too much wear. Check 'em out, you'll be glad you did.