In October 2003, Activision released the source code, enabling the Apolyton gaming community to debug, improve, and add new features.

Maximum army size was increased, some balance adjustments were made to avoid the balance problems from the original Call to Power, and the economic system in Call to Power II was reworked so that controlling good terrain became more profitable.

Another difference is that the player can receive bonuses for certain achievements, if they are the first to perform the action (recapturing a city, sailing around the world, etc.).

Players could, for example, ask the AI controlled civilizations to stop researching some technology, or to reduce their nuclear weapons arsenal.

The sole released patch for Call to Power II enhanced the functionality of SLIC, allowing creation of mods that change the gameplay significantly.

At one point, the members of the Apolyton site contacted Activision and asked them to release the source code to Call to Power II.

[10] Originally, the source code project was accessible through a Subversion server, later development moved to GitHub.

[14] Bruce Geryk of GameSpot highlighted the improved interface, animations and sound, and the game's replay value.