The Skull CTF

by Wokwi

A mind-bending hardware puzzle in three acts

View all updates Nov 30, 2020

Harnessing the Power of the Beaver Moon

by Uri Shaked

Ahoy Mateys!


TL;DR - We need your help tonight at midnight!

A city on the Seine.
Tunnels under earth with
dormant skulls, no brain.
In their faint signals
the answer may pertain.

The cryptic note above was attached to a mysterious package that appeared on our desk this morning. A city on the Seine is undoubtedly Paris, and the tunnels under earth… We’ll get to that in a moment. The package contained what looks like a medieval EEG device attached to a model skull:

And it arrived just in time! We grabbed it on our way out the door, and now here we are: writing to you from 32,768 feet as our private jet speeds toward Paris. Tonight is the full moon for which we’ve all been waiting—the Beaver Moon.

In preparation, we’ve gathered a small army of 208 Cataphiles who’ve agreed to help us invade L’Empire De La Mort, widely known as the Catacombs of Paris, in order to realize the plans we shared previously:

Regarͩdleͧss,ͯ we hăve no cͫhoͦice now but ͬto waͭit. Aͧt midnͦight uͬpon the next full-mooN—the BeAVer Mooon—we will take the victorious Jack to ͧan ancͫiĕntͮ bͥurial ground and ͮcommit what ͣlittlͭe e͒nergy̍ we ͟ha̿vé l̊ef̤t̩ t᷅o͋ t͖h̑e͖ t̿as͊k̓ ̰at̝ ̻h̻̅a̳n̍d:̌ ̭͋e̍x͡tr︠ac︡t̄͊i͜n︣g̹᷇ ͋n᷇e͑︠w͍ ͢͠b̨᷇y̓̓t́e̍́ś ͉͌f̌̇r̮̰o̜̦͡m̢᷾︡ ̊͒͑o̜̭l̵͙̊͞d̗̝,̰̱̹ ̨̽̅t͍͢i᷀́m͎̓e᷂͡w͘o̮͝ȑ̌n̜ͅ ̃̓͑b︡́ò̳᷈̈́n͎̳̾e̵̶̫︠s̫᷀̀̈́ ̔̇͝͠a̪̫᷁᷅ṉ͈͜d̩᷈͗᷁ ̴͌̑̄͞ų̛̼̜͊́s̩̗̃̋᷁͞ͅi̴͉̾̈̈̔̈́͡ng them to complete the skelEton of our ǝɹɐʍɯɹᴉɟ.

But we need your help as well. We ask that you contribute the barest sliver of your life force—tonight at midnight (12 AM CET)—to help empower the ritual of protection upon which we must rely to keep the horrors of the subterranean world at bay.

But don’t worry, it’s easy. Just hold your hands together and say, "Catacombs, Catacombs, Catacombs!". At midnight. That’s all we ask. And wish us luck.

P.S.: Please don’t mention the private jet to Crowd Supply. They are quite strict about how campaign funds are spent.

About the Author

Uri Shaked


$3,298 raised

of $666 goal

495% Funded! Order Below

Product Choices


The Skull

A single The Skull CTF board (☠)


SparkFun Programmer

From the Crowd Supply Basics project.

Design your own puzzles and load them into The Skull's brain using this programmer! Mini USB cable not included.

AVR Pocket Programmer by SparkFun


EconoStik Header: DR VT SMT 2x3

From the Crowd Supply Basics project.

Use with the SparkFun Programmer.

One Amphenol FCI EconoStik™ 2.54mm Header. SMD/SMT Mounting style, Straight angled male pins, gold-plating. Voltage rating: 110 V



Wokwi creates tools for the Arduino and maker community, such as AVR8js, the Open source Arduino Simulator, and GoodArduinoCode.

Uri Shaked

JA Electronics


PCB Fabrication & PCB Assembly

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