A series adaptation of „Tales of Dunk and Egg”, a prequel to the events of Game of Thrones is being made at HBO, based on George R. R. Martin’s The Knight of the Seven Kingdoms.
Tales of Dunk and Egg takes place roughly 90 years before the Game of Thrones plot and is about the adventures of Ser Duncan (Dunk) and young Aegon V Targaryen (Egg).
According to The Hollywood Reporter, HBO has not yet signed a screenwriter for the project.
If all goes well, in 2022 we can see a spin-off series of Game of Thrones that will be about the Targaryens based on George R. R. Martin’s book Fire and Blood. At least Casey Bloys, HBO program director, said that to the best of his knowledge, viewers could get the House of the Dragon in two years.

Previously, it was said that Game of Thrones will have a prequel series called Bloodmoon. This would have taken place thousands of years before the story of Game of Thrones, with actresses such as Naomi Watts or Denise Gough, who dubbed Yennerfer in the Witcher video games. Among the creators, the author of the novels, George R. R. Martin took part as well. A pilot was also shot in Northern Ireland last summer, but reportedly it was so bad, that they stopped making the series.
Sources: telex.hu, variety.com, index.hu