. This specific version, released on January 22, 2025, was a critical hotfix designed to address simulation, UI, and modding issues. Core Update Objectives: Version 1.2.3.f1
If you meant to create a multi-part archive of your own game mods or saves, use WinRAR or 7-Zip and ignore the version number 1.2.3.F1 entirely. That pattern belongs to a non-existent or malicious release.
If you meant a of Cities: Skylines II with that version number, I cannot confirm real features, but expected sequel features (based on announcements before 2025) would include: Cities.Skylines.II.v1.2.3.F1.part02.rar
: The developers optimized the death probability curve so citizens die at more realistic ages. To fix existing "death waves," some seniors were made younger (spanning from early adulthood to mid-range seniors), and the maximum citizen age is now limited to 120 game days Job-Seeking Optimization
: Once finished, you will typically have a single folder containing the update executable or the game files ready for installation. Current State of Cities: Skylines II That pattern belongs to a non-existent or malicious release
: Fixed a bug where electricity production was incorrectly tied to simulation speed Service Vehicles
: It introduced UI improvements and updated the Paradox SDK to version 1.30, enhancing stability for players using community-created content. Current State of Cities: Skylines II : Fixed
Here is why, followed by what you likely actually need:
The most significant "feature" of this update is the overhaul of the citizen lifecycle and death simulation Death Curve Adjustments
If you are updating an existing city, the simulation may experience temporary instability. The patch notes recommend running the game for a while
: You must have all segments (e.g., part01, part02, part03) in the same folder on your computer.