Kingdom Hearts: V Cast (partially found mobile game; 2005)
Kingdom Hearts: V Cast was an unofficial entry in the Kingdom Hearts game series made exclusively for the Verizon Wireless V Cast cellphone network. It was released in Japan on October 1, 2004, and in the United States on February 4, 2005. The game was not developed by Square-Enix, and instead was made by Disney Interactive and Superscape. The game is also not canon to the rest of the Kingdom Hearts series. In 2012, the V Cast network was disbanded, thus making the game unavailable to download.
A dump of the first chapter has been found by "Wedge" of the 4Chan Kingdom Hearts community and has been uploaded to the internet.  However, there is currently no emulator that can play the game. In addition, chapters 2, 3, and 4 are still lost.