The popular word grid game Wordle led to a spat between rival spy agencies yesterday.
MI6 boss Richard Moore voiced his irritation at the trend among players of posting their scores on Twitter, saying he was thinking of unfollowing them.
GCHQ responded to his tweet with an image replicating the game's letter boxes, spelling out the word 'Sorry'.
The light-hearted exchange amused Twitter users, with one describing GCHQ's response as 'top trolling'.
Wordle challenges players to guess a five-letter word within six tries.
GCHQ tweeted 'sorry' in the style of a Wordle grid in response to MI6 boss Richard Moore sharing his frustration at people posting their scores on the social media site
One new word is released every 24 hours - this ensures the online community play at the same time.
Players can then post their result on social media, revealing if they guessed the word correctly and how many tries it took.
Creator Josh Wardle, who was born in Wales but now lives in New York, earlier this week sold the game for a seven-figure sum to the New York Times.
Speaking after the sale, Wardle said: 'My biggest sense, actually, right now isn't joy.
It's relief.'
The New York Times bought Wordle earlier this week for a seven-figure sum from creator Josh Wardle
The media group said it will 'initially remain free' to play, raising questions over whether the game will be monetised in the future.
Wired magazine managing editor Hemal Jhaveri joked: 'If I were the NY Times I'd make Wordle free to play but charge 99 cents to post your score on Twitter.'
She added: 'They'd recoup their investment in a day.'