The director of the UK government's super-secretive snooping agency GCHQ has included a puzzle with his Christmas cards this year, and the public have been invited to have a stab at solving it as well.
It takes the form of a Picross puzzle, a type of challenge you're most likely to have encountered previously on a Nintendo handheld or on your mobile. By following the number rules outlined next to each row and column, the challenge is to use your powers of logical deduction to fill in squares and reveal a pretty picture in the process.
We had a stab at it, on a wobbling train, and after a night out at the Christmas party. The shaky, completely illegible results from our ill-advised formatting approach can be seen below.
Undeterred, we highlighted the completed squares with a marker, which revealed something that looked very much like a QR code. Once scanned in, we were redirected to a new page on GCHQ's website.
The page itself is struggling to load right now, so we can't actually tell you what happens next, although it almost certainly involves our browsing history being fed into a database somewhere, which is obviously great.
According to the BBC, there are a series of increasingly tricky challenges to attempt following this first hurdle, and those who complete all of the puzzles are encouraged to submit their answer to GCHQ before the end of January. If you enjoyed taking part, the agency hopes you'll consider making a donation to the National Society for the Prevention of Cruelty to Children.