My favorite extinct script is the Hsi-hsia script of the Tanguts in NW China (Gansu / Ning-hsia and neighboring areas) ca. 1000-1200 AD. It was modeled on Chinese script and is thus "ideographic". A handful of mostly Russian and Japanese scholars are spending their time on the extremely difficult and rather useless task of decoding it. (but don't get me wrong, that's a good thing). I have read that this very difficult script survived for a time even after the Hsi Hsia state was destroyed by the Mongols.

I have looked for a long time for a font of the Tangut script... finally found one at Mogikyo... went through the time-consuming process of installing their font program... and it doesn't work on my computer! Have you any idea where I can locate a font, or even just a chart of the symbols used by the Tanguts? I sure would be grateful!

Peter T Daniels says: "Kychanov in WWS [The World's Writing Systems (1996), of which Daniels was coeditor] lists a number of works in Japanese by Nishida, and also Grinstead's Analysis of the Tangut Script (1972), which is in a Swedish series that was widely remaindered a while ago."