Game of Thrones almost had a $30 million worth spin-off sponsored by HBO.
In book Tinderbox: HBO's Ruthless Pursuit of New Frontiers, author James Andrew Miller reveals that the network spent a hefty amount in the making of an untitled Game of Throne spin-off that was later discontinued.
As per the book, prominent starts from the original series has signed up to play in the new show, including Naomi Watts. The show would be directed by S.J. Clarkson.
Plot of the series revolved around thousands of years before Game of Thrones, featuring distant ancestors of noble families like the Starks and Lannisters
However, soon after the hefty spent, it was decided that HBO would instead be investing in another spin-off titled House of the Dragon, another prequel set much closer in time to Game of Thrones about the dragon-filled civil war in House Targaryen.