There have been many hoaxes in the video game world on April 1st that are very notable such as those in Electronic Gaming Monthly. Here is a list of well known hoaxes that were on April 1st, or April Fools.
2006 - 5 teenage girls between 16-17 created up to seventeen question mark blocks from the Mario series across their town in Ohio. A citizen noticed one of the boxes and turned it into the police, whom sent out a bomb squad to investigate. Even though there was nothing in the boxes, authorities plan to press charges against the five girls.