Grey space

Grey Space was a region created by the Entity. The Entity was formed of two differently minded entities. One of these was black space and the other wanted white space. As a compromise the two formed grey space. The Entity brought the Doctor to grey space and planned to play Monopoly with him. However, he left in his TARDIS before they could do so. He was brought there a second time in his seventh incarnation and was faced with a RWR Mark II android. He used the password to override it but ultimately failed the test set to him by the Entity. The Entity continued to bring the Doctor's previous incarnations to Grey Space to take the test, each one failing until, finally, the First Doctor passed the test and the Doctors were all deposited back to their respective timelines. (AUDIO: Seven to One)