Diseases Extended for Old World is a mod designed for Windows that introduces a wide variety of new diseases to enhance the gameplay experience. This mod adds ten new deadly diseases, including Malaria, Bubonic Plague, and Smallpox, along with eight additional illnesses such as Cold and Diabetes. Each disease is carefully scripted to reflect the historical mortality rates from ancient times, providing a more realistic challenge. The mod also modifies the existing illness trait system by removing the 'ill' trait entirely, which changes how events and stories unfold in the game.

In addition to the new diseases, the mod implements a variety of adjustments to disease probabilities, allowing for more dynamic gameplay. Players will encounter different threat levels associated with each disease, impacting character courage and event outcomes. The mod maintains compatibility with other mods and requires a game restart after activation for optimal performance. This comprehensive update is aimed at players seeking a richer and more immersive experience in the Old World.