File: Foundation.v1.9.0.21.0919.zip ... -

You are looking for a specific older version of the game to ensure compatibility with certain mods.

If you found this file on a third-party site rather than an official storefront (like Steam, GOG, or Epic), be cautious. Unofficial .zip files can contain malware or outdated, unstable versions of the software.

It is the compressed archive containing the game's executable and assets for that specific build.

Some complex mods require specific builds of the game engine to function correctly.