Can't comment on the game cart so maybe I should not comment....but I will anyway. I thought about getting one and was saving for it, but until I got the money tucked away needed something that would work. Found an old $2.00 plastic taboggin sled in my basement and tried that once and it worked great. It's about 5 feet long so plenty big enough to fit a deer in and the turned up sides help hold the carcass in place and keep the water, mud and muck off of the deer while dragging it though the woods. It's plastic and washes off very easily and only weighs about 2 pounds. It'll skid right over logs, through puddles and very easily through a plowed, grassy or a field still with crops standing in it.
I simply cut a hole in the front (nose) of it, run my drag rope through the hole and around the deers neck and take off. Works very well.
IMO the cart would take up a lot of room in my truck bed. With the sled, I put my rubbermaid clothes container and other junk in it until it's needed.