How can I reproduce a "gamey" flavor?

From a cooking perspective any imitation sauce or marinade is never going to deliver the quality that venison has to deliver. We have a massive deer farm close and the price is still ridiculous . My suggestion is that you find a good butcher that will age beef for you on the bone ,or you could age it yourself if you have a climate control area to keep it at the correct temperature. Anything over 30 days on the bone will start to give you the gaming flavour you are craving. Nothing is going to match deer, but aged beef or really any type of cattle (eg buffalo etc) will give you the gaminess if it is aged. Restaurants are getting up to 180 days, which I could only imagine would melt in your mouth but the flavour would be intense.

As a deer hunter myself, my most favorite part of the experience is the butchering. I enjoy having a knife in my hand and breaking down the big quarters into smaller roasts, chops, etc.

This is where I purposely cut out the gaminess. Gaminess comes from the fat. Venison is very lean, however, it does have some fat, especially in the rib section. Most people avoid the ribs precisely for this reason, too gamey. Yes, you can go in and cut around the fat, but it's just too meticulous. Cut out the fat, and you cut out the gaminess.

Hence, if you want to add gaminess, add venison fat, not beef fat. Beef fat will just make it taste better. To make it taste "wild", add "wild" fat.

Same for other wild critters, remove the fat, and you remove the gaminess. Keep the fat, and you keep that elusive "wild" flavor that you are after.

Beef can make a fairly acceptable venison substitute if you marinate it the same way you would venison. For example, juniper berries are a flavor I associate with venison marinade, so using them on beef gets me that "almost there" taste. It's never quite the same, though; sorry.

I also find it is nearly impossible to find venison. If you can find someone who hunts you may be able to buy some off them, I finally was able to find someone after asking some co-workers. Trying other gamey meats like bison or boar, depending on your local availablity may help but they really don't compare to venison.

Have you tried liver? it has a metalic taste which is vaguely similar and delicious.

The easy way without marination is to use a leg of lamb and lace it with bacon. Stick a medium wide knife blade through the meat and thread a rasher of bacon all the way through the cut. Repeat this 4 or 5 times or more for larger legs. Roast it in the normal manner surrounded by onions and peeled potatoes and peeled pumpkin. Sprinkle the meat with mixed herbs. The flavour of the lamb will be close to venison. Adrian

I basically agree with Burdon on Society's answer; aging is really important. But among the less specially raised and hung meats you might want to look out for hogget, mutton, or goat.

You might also check out the gamiest-tasting cut of beef: the Onglet, or Hanger Steak. It takes very well to marination, and yields a very flavorsome, open-textured meat when grilled or pan-fried.