deciphering tunic
While this post doesn't explicitly contain any spoilers, it reveals several pages of the instruction manual, which could be considered light spoilers if you want to experience the game fully for yourself.
I bought Tunic a while ago when it was on special and I finally got around to playing it last week.
A core mechanic of the game is that the game doesn’t explicitly teach you how to play. Instead, you discover pages of the “instruction manual” as you play which lets you progressively figure out the more advanced mechanics of the game. The catch? The instruction manual only has a small number of English words! Most of the manual is written in a unique script created by the game designers.
One of the first pages you find in the game.
Don’t let that scare you though! The developers don’t intend for you to read the script. The idea was to evoke that feeling of picking up a game as a kid and not being able to fully understand how it works, but giving just enough information for you to figure out the game for yourself. If you ever played classic games like Zelda, you’ll know what I mean.
But is it really text?
At first, I didn’t pay too much attention to the script. A quick skim gives the impression that it could plausibly be text, but there’s no reason not to think that they were simply writing-like scribbles to give flavour to the game. There is enough variation in the glyphs that would mean it’s unlikely to be an alphabetic system (like, for example, the hidden message in the Artemis Fowl books where each symbol corresponds to a different letter). And I’d just started a new game! I had adventuring to do!
But soon enough, the mystery got the better of me and I decided to give it a shot.
Starting assumptions
Where do you start with something like this where you have no information whatsoever? Essentially, you make some basic assumptions, try to make educated guesses, and then you cross-check your guesses with other text and see if those guesses hold.
I assumed:
- The text is English.
- Given the amount of glyphs, the system is some kind of syllabary based on English phonemes, not letters.
- Each group of symbols connected by the centre line denotes a word.
Making educated guesses
With that in mind, I skimmed through the manual looking for text next to pictures that would give a hint to its meaning. This text caught my eye:

Page 28 was a map of one of the main areas of the game. For whatever reason, I thought there was a chance that this text reads, LOST? SEE p.28. I quickly jotted down in my notebook my first guesses:

At this point, I had no idea how those glyphs mapped to those sounds, but this was a good starting point. My next target was the heading on this page:

A very natural guess for this word is, of course, CONTROLS. There was no way to validate this, but with a close look I saw that this could plausibly line up with my previous guess:
Aside: I think I got slightly lucky here, because I only noticed later that the final character here is NOT the same glpyh as the S - it's flipped because it's actually a Z.
Next, I looked at the text next to the shield, which has the potential L glyph in the middle.

I initially thought this might be the word BLOCK, but it didn’t feel right. It was a wild guess, but I pencilled in SHIELD for this word instead (which eventually turned out to be right), giving me a potential glyph for D:

Then, I tackled the page explaining the space button, in particular the two actions on the right, which I had plenty of experience doing from playing the game:

I knew pressing space would do a dive roll, and I knew holding space would let me run. Given that, my guesses here were ROLL and RUN respectively:

By this point, I was relatively confident that I was on the right track. This deduction corresponds perfectly with the guesses for N and ROL in CONTROLS. I still didn’t have a complete understanding of the system, but I decided it was time to give translating a major piece of text a go.
Where else but the first page to start? I went back and scribbled down a gloss for the first couple of words:

That was enough for a big guess: the second and third words were probably SECRET and LEGEND. This added to my set of glyphs:

Consonants and vowels
Now that I had accumulated a set of glyphs that I was relatively certain about, I felt that one of my initial assumptions was not quite correct. I had started by assuming the script was a syllabary. The symbols are clearly syllables since it fits so well, but by this point I felt that there was enough evidence to think that the syllables could be further deconstructed into consonants and vowels.
Notice the similarities in these glyphs:
Note: some of these transcriptions aren't correct and still needed refinement, but they were what I had to work with at this stage.
In particular, assuming the above was true, LE and JE could give the following deduction for the consonant J:

This felt reasonable and turns out to be correct. Once you discover this principal, the rest of the script becomes very straightforward (but a little time-consuming) to decipher. This is left as an exercise for the reader :)
Phonemes vs. letters
A crucial concept of this script is that it uses not the regular spelling but the phonetic pronunciation of a word as the basis of its spelling.
For example, take the words BAIT and BITE. Although BAIT is spelt with “ai”, it’s pronounced EI as in the word BAY. And while BITE is spelt “ite”, it’s this word that actually has the vowel AI, leading to the following spellings:

On the other hand, this means words spelt differently in regular spelling but have the same pronunciation are spelt the same in the game:

The last piece of the puzzle
The script sometimes includes a small circle under some glyphs. I don’t think it would have taken much to figure out what it means even without any clues, but I was tipped off by this hint on page 21:

In fact, it was this clue they motivated me to try to decipher the script, since it implied that there was something more to it than just flavour.
Without the dot, this speech bubble would have read MY STUCK, which doesn’t make sense:

The clue implies that some kind of swapping needs to occur. This quickly resolves itself once you try swapping the phonemes of the dotted glyph around:

giving the correct reading I’M STUCK. In other words, in regular script, the consonant always comes first, but with the dot, the vowel comes first. This gives words like ITEM, which is correctly written

instead of the incorrect
This is the wrong spelling.
Do you speak North American?
A phonetic script for English has interesting consequences because of how many varieties there are. It forces you to pronounce words a particular way, which may or may not be how you pronounce it in your own accent.
For example, many native speakers will use two different pronunciations of the word THE depending on whether the word that follows it begins with a consonant: “the” (/ðə/) banana but “thee” (/ði:/) apple. The designers chose to enforce this difference:

which you can see in sentences like this one:
Inscription reads: THEE (/ði:/) heir hungers for reminders of THE (/ðə/) corporeal world.
As a native speaker of New Zealand English, one thing that stands out to me is that there is only one symbol for both the LOT and THOUGHT vowels (in other words, the cot-caught merger is required by the script):

I (and probably Australian and UK speakers in general) pronounce these words COT /kɔt/ and CAUGHT /ko:t/ respectively, but there is no glyph available for the /o:/ sound.
A further quirk is that the designers seem to be inconsistent with their spelling of schwa (/ə/). Generally, they seem to use both the STRUT vowel (/ʌ/) and the KIT vowel (/ɪ/) for the schwa (and sometimes even /ɛ/, as in LEGEND and ITEM). I’m curious to know why they didn’t add a glyph specifically for the schwa given how commonly it shows up in English, but it means that we see words like CONTROL /kəntroʊl/ spelt /kʌtroʊl/ but BUTTON /bʌtən/ spelt /bʌtɪn/.
Personally, as a Kiwi English speaker, I’d always prefer the KIT vowel (such as the choice of spelling for the “nek minnit” meme), but perhaps North American speakers lean closer to the STRUT vowel?
Side quest complete!
In short - I love this script! It’s a unique idea, it gives a special flavour to the feel of the entire game and it makes a great side quest when you want a break from adventuring.
The design might have been partially influenced by the Shavian alphabet where voiced-unvoiced consonant pairs are also flipped versions of each other (though in the game script they are vertically flipped, whereas in the Shavian alphabet they’re rotated 180º). This means you could make a good educated guess for glyphs when you’re deciphering them. For example, once I had /ʒ/ from TREASURE I could pencil the flipped glyph as a guess for /ʃ/ - though the designers chose not to mirror H and NG like Shaw does in his alphabet.
I also love how the designers chose to style the writing by separately connecting the top and bottom parts, obfuscating how the letters work and makes deciphering the script that much more fun. Consider the word button from the heading of page 13:

The border implies that the top and bottom parts are somehow separate, when the glyphs are actually split like this:

An extreme example of this is the logo of the game, where they fully separate the top and bottom parts of the phrase SECRET LEGEND by inserting the English word TUNIC in-between the top and bottom parts!

This was an amazingly fun side quest and now I feel like I have a superpower! With that, time to get back to adventuring :D