Mega Man Legends 3 (lost prototype of unfinished Nintendo 3DS game; 2010s)
On September 29, 2010, at a Nintendo press conference regarding the Nintendo 3DS, a brand new installment to the Mega Man Legends series, Mega Man Legends 3, was announced for said handheld console.
More information about the game was announced at the New York Comic Con in October of the same year, including two new characters, Aero and Barrett.
Inafune's Leave and First Cancellation
However, on October 29, 2010, Keiji Inafune, who co-created the Mega Man series, announced that he would be leaving Capcom with the intention of "starting his life over" after 23 years of working with Capcom.
With Inafune leaving Capcom, he no longer owned any of his creations and was not allowed to help the company work on Mega Man Legends 3, or create any new installments to the franchise, even if he wished to.
In spite of Inafune leaving the company, they announced that they would be making a special application on the Nintendo eShop that would be called Mega Man Legends 3: Prototype Version, and would include 10 missions. All of them would serve as a prologue to the game's story, and would all have Barrett as the playable character.
The game was slated for a 2011 release, but on July 18, 2011, Capcom announced that both versions of the game had been cancelled and stated that neither would ever be finished or released, despite many denied requests by Inafune to finish the game.
GamesRadar said that the only person who played both games was Chris Hoffman, a journalist who worked for the now-defunct Nintendo Power magazine.
Capcom has held true to their claim, and neither game has been released or leaked in any way since.