is it possible to add german language as an option in the menu ?
You can check this guide here: https://farcry1.itch.io/far-cry-advanced-version/devlog/970294/making-own-locali...
In any case, we were planning to add German lang, but a bit later. Right now all our attention is focused on changes to the engine.
If you would like to speed up the German language addition, you can follow the instructions above(from the link).