On the Subject of Captcha The Flag

Essentially, just work out the solution to the CAPTCHA to help Captcha play Capture. Quite simple really.

This is Captcha the flag. His name is Captcha and he is a flag. He is trying to play a game of Capture The Flag online but is struggling to solve the CAPTCHA to load into the game. Given that he is a flag, that is understandable. You being a human (here’s hoping) need to help Captcha solve the CAPTCHA so that he can play Capture The Flag and so that you can defuse the module.

  • The module consists of a randomly generated 6-character CAPTCHA, two flag buttons, a white viewing panel and a green submit button.
  • In order for Captcha to be able to solve the CAPTCHA himself, it must be translated into the only language flags know - Semaphore.
    Unfortunately, the website he’s trying to play on is slightly broken and, as such, the way you must relay characters to Captcha is as follows:
  • For each character in the CAPTCHA code, submit said character in Semaphore[1] using the two flag buttons provided. Pressing the red flag button will rotate the left flag counter-clockwise and pressing the blue flag button will rotate the right flag clockwise. Your current Semaphore position is viewable in the white viewing panel in the centre of the two flags.
  • If the character in your CAPTCHA is a part of ‘F1AG’, flip both flags for the character vertically[2].
  • If the serial number character in the same position as the character you are currently translating is part of ‘PØLE’, flip both flags for the character horizontally[2].
  • If both of the above applied:
    • Multiply the CAPTCHA character by the serial number character (convert letters using A1Z26).
    • If this number is odd or zero, hold the button with the red flag.
    • Otherwise, hold the button with the blue flag.
    • In either case, do not release the button until the Semaphore fella disappears. This situation is too confusing for Captcha to understand. He is just a flag at the end of the day.
  • Pressing the green button will relay the single character to Captcha.

[1]Semaphore Chart

A 1B 2C 3D 4E 5F 6
G 7H 8I 9J Ø[3]KL
YZOnly here so the table's even


  • Vertical means “up and down”, so to flip vertically is to change up to down and vice versa. It is not possible to flip a flag's banner vertically without removing it from the pole or flipping the pole itself over.
  • Horizontal means “left and right”, so to flip horizontally is to change left to right and vice versa. It is possible to flip a flag's banner horizontally with just a change in the direction wind is going in.

[3]Ø and O Distinction

  • The Ø character (zero), will always have a slash through it on the module.
  • The O character (Oscar), will never have a slash through it on the module.