The biggest problem is when to capitalize words and when to use der, die, das or dem.
Simple rule : If you can put an adricle before the word, then write it in capitals.
The English language is somewhat reduced now, it did have several grammar cases, at least medieval and old English had.
der = grammatically male
die = grammatically female
es = grammatically neutrum
There are words which have a "grammatical sex" which is different rfrom that in other languages. The moon, for example : La Luna (female moon) in the Spanish language, for example, meanwhile "der Mond" (male moon) in German language.
Ships, for example, have been female in the English language for a long, long time, They went into neutrum not too long ago.
And Germans and speakers of other other languages have the serious problem that the English articles "the" and "a" do NOT IN ANY WAY hint the user towards what the "grammar sex" of the word might actually be.
I think Wikipedia might have an good entry article on the language, but on the other hand, it might be a bit complicated, too.
On-topic : The Ankh Trilogy was a huge success and might be avalable in English and in German languages.
Same with Drakensang : If you install it in different directories, it *might* be able to use both language versions … But it might also be that this won't work, because of modern "documents" folders accumulating EVERYTHING …
You could also use games without any spoken words at all, like the "Realms Of Arcania" Trilogy, for example …
Edit : Mr. Mark Twain (known from "Huckleberry Finn") once wrote an article on the German language, which - as far as I know - he absolutely detested.
I haven't been able to read this article so far.
It seems to me that English has become the standard second language, to make it efficient for everyone to communicate, while still having their own languages, too. Seems a pretty good solution. Convenient for the likes of me, of course, but I think that learning a second language is a benefit, not a chore.
It's been easy because the E nglish language is so much reduced. It is so much simple these days.
According to the book "The Loom Of Languages", the current English language is reduced in a similar way as the Chinese language is (minus its letters).