How about a game where you play a health inspector? It could play out LA Noir style, with the overarching plot being determining the source of a massive outbreak of salmonella. Side missions would be things like going undercover at restaurants to get an idea of how sanitary they are, or filing the paperwork to shut down a bar that's been serving burgers made from spoiled meat.

The main collectibles would be take-out menus and secret recipes.