The purpose of this file is to provide users with the option to include German localization in their game or software installation. This could include translated text for menus, in-game dialogue, subtitles, and possibly even voice acting in German.
This file appears to be part of a game or software installation package prepared by FitGirl, a repacker known for making games accessible to a wider audience by cracking their DRM (Digital Rights Management) protections. The "optional-german" part of the filename suggests that this particular file contains German language support or content that users can choose to install if they prefer the game interface and/or audio in German. setup-fitgirl-optional-german.bin
setup-fitgirl-optional-german.bin