Research on Procedural Content Generation typically requires testbed games in order to evaluate the outcome of the methods with human or agent players. In this page you can find a list of open-source games that can be used for that purpose.

Angry Birds

A clone of the Angry Bids game implemented in Unity.  Levels are represented as xml files that can be easily added without compiling the game again. The source code of the game is available on github.

Super Mario World

A clone of the Super Mario World game implemented in Unity.  Levels are represented as txt files that can be easily added without compiling the game again. The source code of the game is available on github.