Weird and Unusually-Flavored Fudge
One good idea is to give each of your guests a bag of ingredients that are often not used in making fudge and then have them compete for the best-tasting fudge. One guest may have a bag filled with jalapeno peppers and mint while another guest may attempt to fix vanilla fudge with herbs such as basil and rosemary. The winner of the contest will receive a dessert cookbook.
Globally-Themed Fudge
If you and the guests come from a variety of cultural backgrounds, you can play a game in which each guest prepares a fudge that's based on a popular dessert in their countries of origin. For example, your Italian friend may prepare a fudge that's based on tiramisu and espresso while a guest from Greece may prepare fudge that tastes similar to baklava, a flaky pastry with nuts and honey. The top three winners will get a gift card to a local bakery.
Fudge with Two Savory Ingredients
Another idea is to hold a contest in which each person will have to use two savory ingredients which would complement the sweetness of the fudge. For example, a guest who is making a lemon fudge may use sea salt and black pepper in the recipe while another guest may use chili powder and cumin in her chocolate pecan fudge. The winner of the best savory ingredient-tinged fudge will get a bag of food magazines.
Best Interpretation of a Popular Family Fudge Recipe
If you're holding a family reunion, you can have a contest in which a few family members compete for the best interpretation of a well-known family fudge recipe. If everyone loves your grandmother's butterscotch-peanut butter fudge, ask them to create their own versions of this recipe. Then have your grandmother taste each version and the winner of the best fudge gets to create the next baking game.