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.
Delay extending the release date of a product due to the manufacturers wanting to add 'new and improved' functions to the product
Feature creap can prolong a release date with infinate delay. see Vaporware
Duke Nukem Forever was a victim of feature creep and is now Vaporware