One year I killed an elk about a mile behind a Forest Service locked gate and used a wheelbarrow to pack him out, 1/2 at a time. The road was pretty much all downhill so it worked pretty well.
Years later I built a one wheel cart with an old bicycle wheel at one end, then a 2'x4' basket in the middle and two handlebars at the other end. I've used it many years in eastern Montana to carry out antelope, and with only one wheel it gets through the sagebrush well. I used it once to pack a 3x3 mule deer about a half mile uphill to a road, and because 1/2 of the weight is held up by the handlebars, it was a tough pull.
I also bought a two side by side wheel game cart from Cabela's and have used it to carry out a number of deer and antelope. Like Rock Chuck mentioned, it's tippy on sidehillls, and both wheels won't fit on narrow trails.
Then a few years ago I built an inline two wheel cart with the wheels under the basket. It has handlebars on each end, but I've only used it by myself. It worked good in eastern Montana packing antelope out, except one time when I tried to cross a wet alkaline wet area. The wheels sunk in and it was a royal pain getting across. I also made it with square steel tubing that was too thick which made it very heavy.
Last year I re-made it by taking off one wheel and moving the single wheel to the center, under the basket. Its a little lighter, but when it's loaded, the weight is high and is a little tippy for one person to use. I've seen advertisements of a similar commercial one with two guys packing out whole elk on it. By myself, I don't think I could get it upright with a whole elk on it.
