Planescape torment is a classic RPG that I have been meaning to play for a long time, but never got round to. I never thought I actually would, seeming as I value my time too much these days to spend a few hundred hours playing a computer game in English - but change the language to German and you have yourself an excellent study tool. Planescape is made by Blackisle entertainment, the people who made the fantastic Baldurs Gate and Fallout series. This game in particular is famous for having a story line with so much dialogue that it is like reading a thick novel. You will spend most of your time reading.
Myself I am playing in tandem with an online dictionary, google translate, and Anki for memorizing new words.
First, find the game at...
For only 6 dollars US.
Then, attach the dialogue patch. I found the BETA sprach patch worked for me.