The wonderful Teh Brawler posted an opinion piece using Pizza as an analogy for the structure of a video game. I highly recommend reading it, it’s a fascinating read and you might not eat another pizza without wondering what video-game it represents.
A condensed version for the incredibly lazy (make sure you read it though!):
The design, rules and controls are represented by the bread / dough of the pizza, tomato sauce is the graphics, sounds and aesthetics, cheese is the story / premise and toppings is the content.
I personally think it’s a surprisingly appropriate comparison. Some further points; both cheese in pizza and plots in video-games aren’t mandatory. Many games exist with no / minimal stories such as how not all pizzas have cheese. In both cases, the absence of both doesn’t always take away from the experience seeing as it is not the focus.
Secondly, all pizzas have tomato sauce such as all games have interactivity with graphics and sound. Games have different styles from your hyper-realistic games to your retro-style pixel games whereas pizza has different amounts of sauce used in conjunction with its other elements, like how a game combines its visual and audio feedback with its story, content and design.