Video game development is a tricky business. Studios with deep pockets and one-man indie developers alike can encounter misfortune, their games exuding hope and promise seemingly falling by the wayside in mysterious circumstances.

The strange thing about the majority of the games on this rundown is that despite concept art, gameplay demos, websites, and E3 appearances, these games have never been released nor officially cancelled.

Some developers – Rockstar included, obviously – can be quite secretive to their inner workings, so we may never know what’s gone on behind the scenes. Others have just disappeared off the face of the earth, despite the odd update over the years hinting that progress is still trundling along.