I've never knocked down an elk where a game cart would've been much help. But when antelope hunting on walk-in areas I've used a wheelbarrow to good effect. the wheelbarrow makes for easy braking on the downhills (push the handles down) and for uphills with a partner all you do is have your parner tie onto the frame in front of the wheel with a rope and pull. The plus side of all this is almost every body already owns a wheelbarrow, so you don't have to invest in a specialized piece of equipment.