Mega Man Anniversary Collection (lost build of cancelled Game Boy Advance compilation game; 2003)
Mega Man Anniversary Collection, originally known as Mega Man Mania, is an unreleased compilation of the first five Game Boy Mega Man video games for the Game Boy Advance.
In 2003, Capcom announced the Mega Man Anniversary Collection for the PlayStation 2, GameCube, and Xbox game consoles. The collection would be a compilation of the eight console Mega Man games with a few extras. A companion collection titled Mega Man Mania was also announced for the Game Boy Advance, which would instead feature the five Game Boy exclusive Mega Man titles with extras, updated and colorized accordingly. The games titled was eventually changed to Mega Man Anniversary Collection, and it was slated to release alongside its console brethren. 
The game was frequently delayed. It was rumored that Capcom had lost the source code for the original games and was forced to reprogram portions from scratch, though a user on the NeoGAF forums denies this rumor by saying that Capcom always archives everything and that the game was cancelled for "stupider reasons". There was also a rumor that the collection was moving to the Nintendo DS, a rumor that Capcom neither confirmed nor denied. Eventually the game was cancelled "indefinitely."
No prototypes of the Game Boy Advance version has surfaced as all that exists about this port are a few screenshots and a few advertisements/promos for the game.
- Mega Man Legends 3 (lost prototype of unfinished Nintendo 3DS game; 2010s)
- Mega Man Universe (lost builds of unfinished PSN/XBLA game; 2010-2011)
- IGN.com: Mega Man Mania Change Retrieved 07 Sept '14
- NeoGAF post that denies the "loss of source code" rumor of the game's cancellation. Retrieved 28 Nov '18
- Mega Man Missing in Action Retrieved 07 Sept '14