They are really good, but I am pretty sure that he won't be able to complete Düsterburg or Reise ins All, escpecially the latter one because of some really hard puzzles - and then the languag barrier... =/

Also, most of the humor will be lost because you can't understand a single word. Just as a really small example from Düsterburg:

Medusa:"Hey, is that a potion in your pants or are you just happy to see me?"
Grandy:"Uhm... I didn't understand that one."
Libra:"But I have. Listen here, snake, that's my man and I wont give him to you!"

Yeah, try to understand a simple joke like that if it's completly written in german.

But I have another suggestion:
http://rpg-atelier.net/index.php?site=showgame&gid=277

I have no idea if you know that game, it's pretty old but was apparently created for a contest to break the language barrier. Therefore, it doesn't contain a single word except for the titlescreen. It's a zeldalike action RPG, if I am not completyl wrong here. Download should be somewhere in here:
http://www.multimediaxis.de/threads/...en-auf-Seite-1