The "DE" in the filename likely refers to the German version of the game, while "CODEX" could imply that the fix is provided by a group known as CODEX, which is well-known in the gaming community for cracking and releasing fixes for various games.
: Use software like WinRAR to extract the contents of the .rar file to a folder on your computer.
: Bypassing the strict DX12 requirement that often crashes the game on startup.
If the fix doesn’t work, try running the game in compatibility mode. Right-click on the game’s executable, select Properties, and then check “Run this program in compatibility mode for” and choose Windows XP or another earlier version of Windows.
: Reducing the frequent stuttering caused by the OS's inability to handle the game's resource management. How the Fix Works