The string "v1.9.0.21.0919" likely refers to the game's version and build date (September 19, 2021). This naming convention is frequently seen on digital distribution platforms or in community-shared archives. What is Foundation?

This specific filename, , appears to be a distribution file for Foundation , a popular survival city-building game developed by Polymorph Games.

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

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