In our own vaporware category we have Society.
You may recall this game that has been in various stages of development for ages.
Here’s a sneak peek GameSpy gave to it from 2005.
It had a number of radical (at the time) ideas such as being “free to play” with a “persistent world”.
So what happened? Basically we’ve been having to wait until the hardware gets to the point where we can do it. We developed our Kumquat engine for this (which is what is now the basis of our current 4X titles in development) but to do a real-time, huge scale RTS, we really need a 64-bit, DirectX 11 style game engine.
So Society may be on hold but it’s not gone or forgotten. It’s just an example of a great game concept whose day will come. Until then, it’ll have to remain in the ether of pre-production.