Another cross-posting :
An additional "source" could be this online, browser-based TDE game site :
http://www.tde-games.com/
"Conspiracy At Ferdok" is a side-story of Drakensang 1, part two of this Adventure (which is called "Death Trail", I think) is commercial.
And - yes, these are official games. Chromatrix is the TDE license holder for all video games based on the TDE rule set.
The only drawback is, that these browser-based games play rather like text adventures. Almost no graphics at all, but you'll get another insight into Aventuria.