Usually includes "New Frontiers" expansions or weekly "Week [Number]" updates (Icarus is famous for its consistent weekly content drops).

To actually access the contents of this file, you generally cannot open it alone. You will need:

v1.2.12.100160. This refers to a specific patch released for the game.

Files named with this specific string format often originate from third-party distribution sites or mirrors rather than official platforms like Steam, which handles updates seamlessly without rar parts.

The .part02.rar extension indicates this is the second piece of a multi-part compressed archive.

Optimizations for the game's demanding engine.

If you downloaded this from a non-official source, always run a virus scan on the extracted folder before running any .exe files, as multi-part archives are a common way to distribute modified software. 2.12, or are you having trouble extracting the files?