Crumble ground beef into a large stock pot over medium-high heat. Add onions, and cook, stirring, until beef is evenly browned. Drain grease, if necessary.
Pour in the spaghetti sauce, water, sugar, tomatoes, mushrooms, pepperoni, bouillon, chili powder and kidney beans. Bring to a boil. Reduce heat, and simmer uncovered for 30 minutes, stirring occasionally, to blend flavors.