My first experience with the X-COM franchise was Terror from the Deep, but once I'd finished it I went on to tackle UFO Defense and X-COM: Apocalypse. All brilliant games in their own way, they forever shaped my gaming tastes. So you can imagine how sick I felt when series creator Julian Gollop revealed the very first game dodged two giant bullets on its way to becoming a finished product.
Robert Purchese over at Eurogamer had a few words with Gollop, with the majority of the conversation spent on UFO Defense (or X-COM: UFO Defense as it was also known). The game designer disclosed some of the massive hurdles he had to overcome to get the game made, beginning with one very critical component -- the design document.
Convincing Microprose, as well as design consultant (and eventual director of product development) Stephen Hand, took a lot of doing:
"I actually had to go there and personally explain things and have a lot of questions thrown at me. Steve [Hand] ... said the document was very poor and if it hadn't been for the fact that we'd done Laser Squad [Gollop's previous game], he would have cancelled the project there and then".
Then, during development, Spectrum Holobyte bought Microprose and one of its first actions was to cancel the project. That didn't stop Microprose from continuing work -- without Spectrum Holobyte's knowledge.
As you can see, it had quite a crazy development cycle -- I'd recommend hitting up Eurogamer for the full retelling.