I have a very similar story, except I taught myself and a friend to write using "daedric" from Morrowind. I don't know if it was the actual daedric letters from the game, I think I just found a font that claimed to be daedric from a website and thought it was really cool. My friend and I would write notes to each other in this little secret chicken scratch-looking alphabet, it was fun.
I sometimes try to remember how to write it or how to read it (I still have some notebooks from when I was a kid as well), but it's been 20+ years and I only recognize a few characters at this point. The rest is practically Greek to me now.
I don't speak Korean, but I'm a language nerd. Sometimes for fun I write Finnish in the Hangul alphabet in my journal (requires some approximation/adaptation).
I'm not understanding how this makes it easier to write in the dark. I'd think handwriting in cursive or even printing would work OK. In fact I just tried it and it was perfectly legible.
As a child I made several crypto disks out of cardboard, draw a 3 inch circle, give it enough segments to fit your alphabet, 32 is easy and gives you room for the capitals and some punctuation, draw the letters twice on each segment inside and outside of the circle, then cut out the circle, glue the outer part to a backing sheet and glue a tab/handle to the inner part to make it easy to spin.
Used statically it works as a simple ceaser cipher, but the real advanced ciphers became available if you rotated it by a specific amount after each letter.
Many plans and conspiracies about what we were going to do with our new "unbreakable" encryption system, but in retrospect, never used and more fun to build and think about than operate.
https://en.wikipedia.org/wiki/Cirth#Runes_from_The_Hobbit
I got to the point I could read and write without a reference. Not as fast as English but not slow either.
Many years later I found a notebook with many pages of things I'd written but had since lost the ability to read again.