Hangul in general is pretty smart in general. You can get the hang of it in an afternoon, which is something you cannot say about the Korean language in general.
I'm guessing it was top to bottom and then during the modernization process, left to right was added? It's smart that both forms are allowed though as I could imagine modifying a written language takes many years and massive public effort.
Yep, it used to be top to bottom, and the columns were arranged right to left. As a side effect of this recent transition, it's not particularly difficult to read Korean right to left, either.
It's the same in Chinese and Japanese. It helps a lot that the letters are designed fit into individual square blocks. The blocks can be arranged any way you want. There have been internet memes, for example, written to mean one thing when you read left to right and a completely different thing top to bottom.
But yes, Chinese was written top down, right to left. The PRC basically switched over to left-right, top-bottom right away (it kind of went hand in hand with the simplification project). Taiwan for example kept the traditional format for a lot longer.
When I was learning Mandarin in the late 90s, all our imported material from Taiwan was still top-down, right to left.
The traditional way is vertically, indeed, but on occasions you had to write horizontally, which was then usually also done right to left (can still be seen here and there, as I mentioned in my previous comment).
At least for Korean, it was right to left only when written top to bottom. Then it changed to left to right. It's never been right to left horizontally. I think it's the same with Chinese. I'm not sure about Japanese.
I've read that there are Arabic-Chinese dictionaries where Chinese is written from right to left to match Arabic direction of writing, but I don't know how common this is.
Do the individual syllables also reverse direction? They're normally read left to right and top to bottom. I'd imagine that they're taken in as complete syllables by readers rather than read sound-by-sound, so they maintain left-to-right.
