1-18-3-1-14-21-13
Solution document

Overview Conclusion, Extra Terra, and more

Aer

Aqua

Ignis

> Terra

# Terra

Terra is split into 7 sublevels: Sol, Luna, Mars, Mercurius, Iuppiter, Venus, and Saturnus.

## Sol

Sol depicts a sun with 13 rays. Each ray contains 20 white lines, while the inner core beneath each ray has different amounts of black lines. White and black are opposite colors, so count the amount of black lines in each chunk and calculate the difference.
For example, the very first chunk has 11 black lines, thus the difference is 20 - 11 = 9. Doing this for all 13 chunks in a clockwise order from the very top gives: 9 14 6 5 18 14 1 12 6 12 1 13 5
Decoding this from A1Z26 gives infernalflame, which is the answer.

## Luna

Luna contains 13 interconnected circles separated into two groups, next to each are 3 symbols that are either a dot, a line, or two lines.
Interpreting dots as 0 and lines as 1, the symbols give 13 base-3 numbers. Reading each number from top to bottom gives 011 120 200 201 210 111 and 010 210 201 022 111 001 112, which when converted to decimal gives dorsum and cushman. Thus dorsumcushman is the answer.

## Mars

Mars depicts a map. Adjusting brightness on mars.png reveals 2 formulas surrounded by a <title> tag:
And the text motto? in the upper left corner.
The <title> tag is a hint to the page titles, which uses a custom alphabet that at first glance seems like gibberish, but the titles actually spell out element and planet names.
Documenting each page title gives the following custom alphabet set: (unused letters not included)
ACEGILMNOPQRSTUV
4;§+6¼592í?êù‡¤1

Using this custom alphabet, the formulas become 1/4 * (152-2.16) and (295.62+6!) / (2*4), which gives 37.46 and 126.9525. This can be interpreted as a coord, which would lead to Seoul National University at Seoul, South Korea.
With the motto? text from earlier, it is decucible that the motto of Seoul National University Veritas Lux Mea is the answer, which the extra confirmation page confirms it.

## Mercurius

Mercurius contains multiple white squares. Viewing this as a 8x8 square where each cell is either black or white, a transcription can be made:

 01001001 01000101 01001110 01000100 10101110 01000010 01100000 10000010

Each line is an 8-bit binary number. Although not every line points to a printable character, converting the 8 lines from binary ASCII would give IEND®B`., which is the PNG end-of-file signature.
When checking the end section of mercurius.png in a hex editor, additional text and an RAR file can be found appended to the file.
The text, which is surrounded by dots, is also 8x8 like the picture, and the RAR file is password protected.

 ndhyezsu lsctvmqe lrracats tueofrkl axerdeuy ysnnsulq kucnbaqe rypqnbiv

Overlaying the original pic above the text (or extracting text where white squares are), reading from left to right then top to bottom, the text deusmercaturaedeuslucri can be extracted.
Extracting the RAR file with deusmercaturaedeuslucri as the password, a mercurius.txt can be obtained, which contains:

 once you've solved this step, the resulting string will be the plaintext. no further decoding needed. 24535 22622 13229 373 24395 20216 8673 18937 14021 5401 5401 13229 8986 9458

With the Codex Arcanum the numbers can be converted into words:

 alfa mike golf victor oscar juliett november hotel sierra echo echo golf uniform initials

Thus take the initial letters of each word, this gives amgvojnhseegu. While it looks weird, it is indeed the answer.

## Iuppiter

Iuppiter consists of a picture and 13 pairs of letters. The picture on top is depicts the construction of a line that passes the midpoint of a line segment, so this level is about finding midpoints between the two letters.
The method involves a QWERTY keyboard. For example the first pair, BQ, the distance between B and Q is 2 keys vertically and 4 keys horizontally. Thus the midpoint of B and Q would be the key that is 1 key vertically and 2 keys horiziontally away from both B and Q, which in this case is D.
Do this on all the pairs and the word dieffenbachia can be obtained.

## Venus

Venus contains a text and an hourglass in the background. The hourglass is a hint to time, which can be checked with EXIF. This shows that the create date is April 5th, 1523, as well as a text in the comments:

 A victim of Stigler's law, but the work lives on, for the sixth key you must find him, and use him in his native tongue.

April 5th, 1523 is the birthday of Blaise de Vigenère, who is famous for NOT inventing the Vigenère cipher, but rather for having the cipher being named after him.
Stigler's law (of eponymy) states that "no scientific discovery is named after its original discoverer", which in this case the Vigenère cipher was first described by Italian cryptographer Giovan Battista Bellaso.
Thus decoding the text in Vigenère cipher with the key giovanbattistabellaso and the letter set ABCDEFGHILMNOPQRSTUVZ, which is the Italian alphabet, gives an Italian text:

 Langue in me l'eco infranto, Al truce sguardo dell'angelo cieco, Rovina in me l'antica rima, Nel cuor del cigno ferito e morente.

This is the first verse to Rhapsody of Fire's Lamento Eroico, and thus the answer is lamentoeroico