One government agency in England celebrates Christmas a little bit differently than most.

The GCHQ — Government Communications Headquarters — provides security and intelligence services for the British government. Back when they were known as GC&CS — Government Code and Cypher School — they were responsible for funding the Bletchley Park successes cracking the German “Enigma” code during World War II.

And for Christmas this year, they’ve released a puzzly Christmas card that’s sure to challenge even the staunchest puzzlers.

Step 1 of the puzzle is a logic art puzzle where you have to deduce where to place black squares on an open grid in order to form a picture.

Each column and row has a series of numbers in it. These numbers represent runs of black squares in a row, so a 1 means there’s one black square followed by a blank square on either side and a 7 means 7 black squares together with a blank square on either side.

Once you’ve solved this puzzle, you can use it to unlock the next puzzle in the chain.

From an article on GCHQ.gov.uk:

Once all stages have been unlocked and completed successfully, players are invited to submit their answer via a given GCHQ email address by 31 January 2016. The winner will then be drawn from all the successful entries and notified soon after.

Players are invited to make a donation to the National Society for the Prevention of Cruelty to Children, if they have enjoyed the puzzle.

This is one majorly challenging Christmas card. After you’ve conquered the logic art puzzle, you’ll confront brain teasers, palindromes, pattern-matching, deduction, number progressions, codebreaking, cryptic crossword-style cluing, and more.

I would highly recommend teaming up with another puzzle-minded friend (or more) and trying your luck. Let us know how far you get! (And you can hit up this article from the Telegraph for aid as well.)

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