Twistian-Wistian, the language of Twisty-Wisty, was my first conlang. As far as I recall it existed only as a dictionary in an exercise book; it was really just a coded English, with no grammar of its own, and if I ever used it to construct so much as a sentence I have no recollection of it. But then the whole point of it, in the spirit of Twisty-Wisty, was to be an absurdly impractical language.
All I recall of it is that in was ofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofofof, give or take a syllable or two, and of was inininininininininininininininininininininininininininininininininininininininin. Otherwise the vocabulary did not much resemble English, though I suspect it did follow English phonotactics.
What I find most remarkable about this language is that I found it a worthwhile exercise: it would never be used for communication or cryptography, it was ridiculously impractical even for personal use, and yet I wrote the dictionary. I conclude that this was a pure, if childishly simple, artlang.