Creating video games is an incredibly difficult process. Most developers go into a project with gleaming eyes, hoping that they can make the gaming equivalent of the second coming. And that's a good thing. Studios who set their eyes on the sky often create masterpieces of pure interactive brilliance.
However, that often comes at the price of having the occasional genuinely outstanding idea brushed to the side for the sake of time and focus.
The list of cut mechanics is inevitably longer than the list of implemented ones, and hearing about features that were going to be included can be pretty interesting - not to mention disappointing. Sometimes what hits the cutting room floor is so ingenious that it's annoying to realise that you likely aren't going to be able to play through some of the waylaid content that was planned.
With lots of developers revealing design details from old games and some technology whizzes uncovering buried files in various games' code, there is no better time to dissect forgotten game mechanics and ideas that could have changed the landscape of the industry... had they only not been trashed.