Likely internal build numbers used by the developers to track specific hotfixes and patches.
Unlike platforms that require a constant internet connection or client-side authentication, GOG releases allow the user to own their installers. Foundation.v1.9.0.37.1117-GOG.rar
The "GOG" suffix in the file name is critical. It signifies that the game is "DRM-free" (Digital Rights Management-free). Likely internal build numbers used by the developers
The .rar format indicates a high level of data compression, used to bundle the game’s assets—textures, scripts, and engine files—into a single, portable unit. Impact on the City-Building Genre used to bundle the game’s assets—textures