'Bridge of Birds', Hughart's first book, won the 1985 World Fantasy Award for best novel.
It's a lovely romp, with puzzles, mazes, love affairs, drunkeness, quirky characters, crazy escapades, strange rhymes, inventive trickery, tiger-masked dukes, the Queen of Ginseng, invisible monster hands, lost goddesses, faithless handmaidens and an almost wholly invented (or at least embroidered) history and mythology of China. It's loopy without being annoying. I was sent this as a being-stuck-in-hospital present, and I swear that it made me feel a whole lot better very fast.
If you can get hold of it, grab it, run out of the shop cackling with glee, and shut yourself away for a few hours to read it in one sitting.
Oh, and the visit to hell mentioned above takes place in The Story of the Stone, the second of the three Master Li and Number Ten Ox books. The third in the series is The Eight Skilled Gentlemen.