Feb. 3 (UPI) -- Author George R. R. Martin said he has been hard at work on The Winds of Winter, but still doesn't know when he will finish the sixth novel in his A Song of Ice and Fire series.
The books served as the foundation for the iconic HBO fantasy drama, Game of Thrones.
"I wrote hundreds and hundreds of pages of The Winds of Winter in 2020," Martin wrote in a blog post Tuesday.
"The best year I've had on WOW since I began it. Why? I don't know. Maybe the isolation," he added, referring to social-distancing in practice since last March to slow the spread of the coronavirus.
"Or maybe I just got on a roll. Sometimes I do get on a roll. I need to keep rolling, though. I still have hundreds of more pages to write to bring the novel to a satisfactory conclusion. That's what 2021 is for, I hope. I will make no predictions on when I will finish."
The last A Song of Ice and Fire book, A Dance with Dragons, was published in 2011. Martin began writing The Winds of Winter soon after that.
Game of Thrones -- which starred Nikolaj Coster-Waldau, Peter Dinklage, Lena Headey, Emilia Clarke, Kit Harington, Sophie Turner and Maisie Williams -- ran for eight seasons and initially aired 2011-19.