Vaporware is usually related to a game, such as Duke Nukem Forever, that is always talked about and hyped but never actually completed.
Duke Nukem Forever
Software that has been delayed so long that it will never be released.
Duke Nukem Forever was first to be made on the Quake engine, then the Quake 2 engine, then the Unreal Engine, then the Unreal warfare engine, its six years past its release date... face it, its never coming out.
Anything (usually software, but can be anything) that is promoted and marketed without ever actually being produced.
When I started Vaporware Records, I did so with the idea of never making an album but starting chaos none the less.
computer software that is announced but does not yet exist due to being stuck in development or being canceled all together
Duke Nukem Forever has become an infamous example of vaporware.
Software that does not exist or has not been programmed yet.
Streets of Rage for X-Box
is an example of vaporware.