Rimworld.v1.4.3580.zip

If you are playing offline, many modders keep "Legacy" branches of their mods specifically for 1.4. 3. Updating to the Latest 1.4 (or 1.5)

It looks like you are referencing a specific archived version of (v1.4.3580). If you are looking for a "piece" in the context of a missing file, a mod, or a specific fix for that version, I can point you in the right direction depending on what you need. RimWorld.v1.4.3580.zip

Look in your Windows Defender or antivirus history. If you are playing offline, many modders keep