Design Criteria for Alternate Alphabets

Like many children, I created some alien and fantasy alphabets when I was younger.
I did not understand about phonemes back then, so these were actually simple character substitutions.
I was remined of this recently when a colleague jokingly offered to send me a message in Windigs. I responded that I could reply in Tenctonese font. I am pretty certain he did not understand the reference.

Criteria for New Alphabets

Some of my criteria for creating a new alphabet have been overtaken by technology. Most of our correspondence is now entered by keyboard or the equivalent. A device can form any letters with equal ease.
• The most used characters should be quick and easy to form. My last attempt only got as far as the vowels and a few consonants.
• Characters should be easily formable by a single pen stroke.
• Readers distinguish characters by the upper half, so that should be where the distinctive features are.
• No character should closely resemble another. For example: l, I, 1 (el, ai/iy, wun)
• Characters that are inverted or reversed should not be confused with other characters, including those that are alphabetic, common mathematical, punctuation or numeric. The chracter for number six may be mistaked for a nine, or sometimes an eight.
• Character combinations should not resemble other characters. No more “m” or “rn”.
• Possibly, classes of similar letters might share some common distinguishing feature while still remaining distinctive from each other. I am thinking of Sona’s division of the alphabet into 6 vowels, 6 aspirates, and two groups of 6 consonants, or Shavian voiced/voiceless pairing.
• The most commonly used characters should have some logical resemblance to traditional/Roman/English alphanumeric. ^ for A/a, `for i/I, – for e/E.