The Mother series (aka EarthBound series) is a Nintendo franchise primarily the brain child of Shigesato Itoi. The games have built an intense, strong cult following for it's unique humor, setting, and gameplay.
Unlike other RPGs, the Mother games take place in a modern day setting, where psychic young boys team up with martial artists named Poo, to fight Abstract Art, New Age Retro Hippies, and Ramblin' Evil Mushrooms. The games have been described as being some of the first postmodern video games.
The first game, Mother was released in 1989 for the NES. This game was never seen outside of Japan, though it was fully translated into English and ready for release. Fans would later be able to play the game when a ROM is leaked onto the internet. Six years later, the critically acclaimed EarthBound / Mother 2 is released. This one makes it to North America.
The first two Mother games were a success in Japan, becoming a popular series. It was believed this boom would be duplicated in North America, but it receives little fanfare, except for a strong cult following. Little is heard about the series since then, until Super Smash Bros. for the Nintendo 64, which features the relatively unknown Ness as a secret character. This gives fans hope for the future, as well as drawing attention to the forgotten SNES game.
EarthBound 64 is announced, and many screenshots are released to the public as it is being developed. However, in 2000, it was announced that the game had been officially cancelled. Fan communities like Starmen.Net create campaigns, including gathering 30,000 signatures on an online petition. This petition was printed out (600 pages), and sent to EGM, Shigeru Miyamoto and Shigesato Itoi, along with art and letters in both English & Japanese. At the very least, this had Miyamoto acknowledge their existence, referring to the petition in an interview. 
Super Smash Bros. Melee was released a few years later, but still no news of a new EarthBound game. A GBA port featuring the first two games in a package called Mother 1 and 2 is announced, though, and during its commercial, they reveal that Mother 3 is also in development for the Game Boy Advance. It is finally released in 2006, after one decade of waiting. It is believed this is the last EarthBound game, according to Itoi. There are no plans of a release outside of Japan.