Word for hard-to-understand writing style [duplicate]

I am looking for a word that could be used to describe a writing style that uses lots of uncommon words, making the writing difficult to understand to the everyday reader. It's as if they make an effort to use words from their word-a-day calendar.

Andrew's _______ writing style used so many words I had never seen before, making it very difficult to understand his point.

The word pretentious comes close, but it implies that the writer is intentionally doing so to sound more intelligent than they are. I would like a word that removes intent and only describes the writing, not the writer. I want to allow for the option that the writer is in fact very intelligent and just doesn't realize that other people don't have as large of a vocabulary.

I should also mention that I would prefer a word that doesn't fit this definition itself, so a word (or hyphenated set of words) that is not too uncommon. I'm trying to avoid the irony of using a little-known word to describe someone's use little-known words.

You might call it obtuse:

2b: difficult to comprehend : not clear or precise in thought or expression
_{definition from m-w.com}

“Magniloquent” might work. Whether or not it fits with a good flow, that’s another story.

Using high-flown or bombastic language.

(Oxford online Dictionary)