I'm sure I've come across something similar before, but don't know where.
DS1 is currently fascinated with language and grammar.
For fun - I know - he has been deconstructing Christopher Paulini's invented language in Eragon and working out what the grammatical rules are, and how the language works; so that he can write new spells and curses himself.
and I thought how much more fun to do start doing this with a real language.
I could create something myself in German for him to work out what the rules are.
But I'm sure something similar must exist already ... somewhere?