The Origins of Liyahu
Liyahu began as a gimmick for a conceptual RPG that I've had in mind for a long time. A central theme in this RPG is archaeology. To make things more interesting for the player, I wanted to create a forgotten language used by a long-gone group of people. Players would discover this exotic language as they explore the caves and ruins inhabited by the ancients.
The trinity has always fascinated me since I was a young adult. The idea came from the Dianetics book (I'm not a Scientologist) I read in 1997-98. The main idea that impressed me was the interplay between the three entities of mind, body, and soul. The number 3 is also an important, mystical, and flexible number. It's balanced (cf. rock-paper-scissors, triangle is the sturdiest shape), simple, repeatable, expandable, etc. More recently, I learned about ternary logic and how much better it is than binary (true/false) logic. (Aside, I'm designing a programming language with ternary logic as one of its core.) Also base-3 numbers are actually more efficient than base-2.
Back to Liyahu. The first roadblock is how would my letters in this alphabet look like. I saw other constructed languages based on concepts of 2 and 4. They usually put symbols side by side or in a square. Similarly for my base-3 writing, I decided to divide my letters into three parts. Hence, the skel (short for skeleton) that is shaped like a Y. The letters would be combinations and permutations of smaller symbols arranged around this skel.
The symbols for mind, body, soul came about quite simply. Mind is a vague outline of a (human) brain, separated by left and right halves. Body is an upright (human) body. Soul shows the four chambers of the (human) heart (as well as a cross pertaining to many spiritual philosophies, including ancient Babylon and Egyptian, Christianity, and Hinduism.)
With the symbols set, the next major hurdle is connecting them to the sounds used in speech (in particular, what our human voices can make.) Many alphabets in real-world languages comprise about 20 to 30 letters. Coincidentally, I can fit around that much using single and double symbols: 9 singles and 27 doubles = 36 letters. Thus I reserved 9 single letters for vowels and 27 doubles for consonants.
I sought the 3 most common, yet distinct vowel sounds found in languages around the world, and concluded these were A, I, and U. Then connected them to the trinity: A is the sound of physical release (e.g. when a fighter is about to punch), U is the sound of breathing central to many spiritual activities (e.g. yoga, meditation, hu is also the Mandarin word for exhale), which leaves I for mental activities. Another reason for choosing these 3 vowels, is that according to the IPA vowel chart, these 3 vowels occupy the corners of the chart. So, there is plenty of room between them to locate other lesser vowels and group them closest to the major vowels.
Consonants will contain two symbols in specific permutations. However, repeated symbols are rarer than combined symbols. That is, there are fewer mind-mind permutations than mind-soul. Hence, repeated symbols shall form the basis of consonants. For these, I sought out the glides, semi-glides, and pharyngeal sounds. First, there are fewer of these sounds than 'harder' consonants. Second, it distinguishes this language from real-world languages, which usually form around 'harder' consonants. Third, they sound smoother and less effort to pronounce. Liyahu comes out smoother than say, Bikatu. Also important is how close these sound to the essence of mind, body, soul. YA is the sound of physical release. HU is the sound of breathing. LI is the root of words like 'literature', 'letter', 'library', etc. (Thus I also defined 'li' in this language to mean 'letter'.)
The rest of the consonants are organized by family of sounds according to linguistic theories. Where the sound comes from (throat, nasal, mouth), position of tongue and teeth, voiced, aspiration, etc. Then fit these groups as best with the concepts mind, body, soul, along with the sounds of A, I, U.
The choices of vowels and consonants are highly influenced by English, Cantonese, and Mandarin.
The names of the vowels is simply the base consonant sound--L, Y, or H--plus the vowel sound. For example, E belongs to I group, which is related to L. So L + E = le.
The names of the consonants is simply the consonant sound plus the vowel in the empty position of the symbol. For instance, L is missing the right symbol, which is the default position of the soul symbol, or U. Hence L + U = lu.
The default positions of the symbols situated around the skel is thus: mind at top, body left, and soul right. This has other ramifications for other matters, including 3-symbol letters, word composition, alternative writing systems, structural concepts (such as past, present, future), etc.
Words are created where each letter represents a process and property of that word. For example, the word for fire is 'hus'. H (soul-soul) means it has no physical state. You can't hit it or hold it. U (soul) means it moves around like a breath of air. S (soul-body) means it can warm the body and the heart. Fire also makes a sizzling sound. Thus, individually each letter for the word fire 'hus' and together embodies the essence of fire. (It also sounds very close to the Mandarin word for fire 'huo'.)
The variant writing systems began as a way to facilitate writing Liyahu with pen and paper. Variants 7 and 2 came first. However, the forums posts goes by the order I have in my notebook, where I experiment and practice the different writing systems. I must say, variant 2 is actually quite fun to write with pen and paper (and looks cute to boot). As you said, simple symbols, trimmed to the essential, make things efficient and practical. Then I expanded to wildly other forms of 'writing', although some of these seem more fanciful than practical. Variant 11 is inspired by Phyrexian writing (from Magic: the Gathering card game), through which I learned about ancient Incan communication methods that tied ropes and knots called 'quipu'.
One of my most ambitious, fanciful idea for the RPG is to have different writing systems appear on different parts of the game (i.e. on different worlds and levels).
(Note: This post is a response to Napishtim's questions via PM.)