Most media have some kind of setting. A world, a time, some characters, maybe some Backstory... but not here. There's only one thing for you to see or do here. No frill, no fluff. Most often seen in Retro Gaming, originally due to programming constraints but now mostly for style in the Casual Video Game. When used in video games, the main reason for not having any story or characters is generally because the player's not going to be interested - the Casual Game is meant for pick-up-and-play while waiting for the bus or something. Expect Rule of Fun to be invoked, and often. This is a trope that video game producers may have to consider more in modern times, as nearly every modern game is expected to provide some form of story instead of just pure gameplay.