Preheat Oven: Preheat your oven to 350°F (175°C).
Sauté Aromatics: In a skillet over medium heat, sauté the chopped onion until softened and translucent, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant. Remove from heat and let cool slightly.
Combine Ingredients: In a large mixing bowl, gently combine the ground venison, ground pork, breadcrumbs, cooled sautéed onion and garlic, eggs, milk, 1/4 cup ketchup, 2 tablespoons Worcestershire sauce, thyme, rosemary, salt, and pepper. Use your hands or a large spoon to mix until just combined. Don't overmix!
Shape the Meatloaf: Transfer the mixture to a 9x13 inch baking dish. Shape it into a loaf, mounding it slightly in the center.
Prepare the Glaze: In a small bowl, whisk together the 1/2 cup ketchup, 2 tablespoons Worcestershire sauce, and brown sugar.
Glaze the Meatloaf: Pour the glaze evenly over the meatloaf.
Bake: Bake in the preheated oven for 1 hour, or until the meatloaf is cooked through and the internal temperature reaches 160°F (71°C). Let the meatloaf rest for 10-15 minutes before slicing and serving. This allows the juices to redistribute.
Slice and Serve: Slice the meatloaf and serve hot.