Europa Universalis II is, a it's predecessor, a highly open game. Most of the core files used by the game are text-files editable for any user. Graphics are stored in open formats, and are also easily editable with the right skills and software. This has also spawned a high interest for modifying the different scenarios and making new ones. Many of these modifications are discussed in the Scenarios, events and modifications forum at the Europa Universalis official forums.

I have compiled a Scenario Editing Guide for those who want to create new and edit existing scenarios in EUII. See also the Country Creation Guide for a crash-course in adding new countries to existing scenarios.

One of the more exciting new features of EU II is the new event engine. This allows scenario creators and modifiers to make their own events for countries, or groups of countries, thus making the game event more fun to play. The event engine is open, and all events can be created in a simple text-editor. The Exhaustive Bible of Event Scripting explains how this work.

Most of the files in EU2 can be edited. The File Edit Guide explains what can be found where, and what you can do with it.

The guide has now been updated to reflect status under the latest, probably final, version: 1.09. Many thanks to the people on the Paradox forum for pointing out the errors of the site as it was.