The Final Game (unproduced TV story)

✅

The Final Game was an unproduced serial written by Robert Sloman and intended to end Season 11.

It would have revealed the details of the relationship between the Doctor and the Master: either that they were actually brothers or the Master was an amalgamation of the Doctor's darker personality. This story originally ended with the Master sacrificing himself in some sort of explosion, with a moral dilemma that should he set off a bomb as intended, he would be killing the Doctor, his former friend. (DOC: The Final Curtain)

However, the serial was never produced due to Delgado's sudden death. Instead, Planet of the Spiders replaced this story, and Delgado's character was shelved until The Deadly Assassin, which recast the Master as Peter Pratt, in a decayed state.

Legacy
This story was adapted into a non-profit audio serial in 2018-2020 in honour of the centennials of Roger Delgado and Jon Pertwee.

Several elements from this episode have been recycled throughout the years:
 * The Master causing the Doctor to regenerate occurs when the Tremas Master caused the Fourth Doctor to regenerate. in TV: Logopolis.
 * Their possible fraternal relationship was teased in TV: Planet of Fire by the Master to the Fifth Doctor and Peri Brown, though TV: The Sound of Drums later dismissed this theory after the Tenth Doctor was asked this question by Martha Jones.
 * The idea of a corporeal "dark side" was used in TV: The Trial of a Time Lord, when the Master reveals that the Sixth Doctor's prosecutor, the Valeyard, was in fact a manifestation of the dark side of the Doctor's own personality. Search for the Doctor also suggests that Omega is an opposite side to the Doctor.
 * The original ending occurs in TV: The End of Time when the Saxon Master sacrifices himself to save the Tenth Doctor from Rassilon. However, the Doctor regenerates soon afterwards due to unrelated radiation poisoning.