Easter egg

An Easter egg is a hidden message or feature in a video game. They are different from other secrets in games, such as unlockables, because they are usually especially hard to find. Easter eggs are often jokes. Many easter eggs, by design, go unnoticed.

Famous easter eggs

 * Adventure
 * Dopefish
 * Sam (of Sam & Max) in various Lucasarts video games
 * John Romero's head in DOOM II: Hell on Earth
 * Portraits of Mario characters in Zelda's Castle in The Legend of Zelda: Ocarina of Time.