Johnny Castaway may not be a game, but it is more than just an ordinary screen saver. The screen saver tells the story of Johnny, a man stranded on a desert island. Normally, he will just sit around, read, sleep, and fish. However, there are many special events that will happen over time. Pirates will come to the island, he meets a mermaid, and he may even try to do a rain dance to battle the heat.

A lot of the events that occur are based upon the computer's system clock. For example, there is a pumpkin on the island around Halloween and christmas decorations in December. As the screen saver progresses, certain animations will reveal more about the story. Eventually, the story is revealed and it is shown why Johnny is stranded on the island. There are so many different events that happen during the screen saver that people are still documenting them and believe they can still find more.