Patches and hotfixes are free updates for Crusader Kings III, though there they are different in purpose:
- Patches fix many bugs and/or implement balance tweaks. They are sometimes released alongside a new, major DLC; when this occurs a portion of the DLC's features are usually shipped as part of the coinciding free patch, thus made available to anyone who has the base game.
- Hotfixes are very small updates to the game that usually fix only a few bugs and may contain a few changes to the gameplay as well. Hotfixes are commonly released shortly after major patches to fix any unforeseen bugs that came with the previous update, or independently to fix newly-discovered bugs or exploits.
- Note that newer DLCs cannot be activated if you're playing on an older patch version. This is also applies to mods, which have various levels of compatibility with new patches.
Each patch has an associated checksum that allows to verify the installation is correct.
It is displayed at two places:
- On the CK3 launcher: it is the reference/expected checksum (hardcoded).
- On the game lobby, in the bottom left: it is the actual checksum, dynamically calculated from the loaded game files.