The Microsoft Age of Empires II update 2.0a to fix a number of issues with the game. These updates include:

* Town Center changes.
* Improved performance of single player campaign games.
* Improved overall stability.
* You can no longer use a fishing ship to build buildings other than a fish trap.
* The cooperative farming bug has been fixed.
* A number of computer player and scenario editor bugs have also been fixed.

This patch includes the previous AI update which addresse the issue where the computer player resigns after a few minutes of play. It does not affect multiplayer, meaning players with the update can play with players who do not have the update.