Yakumo is an exploration of the different technologies used in making a modern game, including graphics, physics simulation, 3D audio and content creation pipeline design. This book follows the processes involved in implementing a game which integrates all of these components, based on using OGRE 3D for graphics and Havok Physics for real-time physics simulation. This book also tackles common issues with such software, such as creating a camera that does not clip through surfaces, writing multithreaded code, and supporting reliable network communication. Implementation of an I/O library for iPhone OS devices is also described. This allows physical input to the game by taking advantage of the many sensors of the iPhone/iPod touch, including accelerometer and touch-screen input. In 2009 this book won the IBM Open Source Competition award (University of Limerick, Ireland). All technology produced during this project is released as open source software under the Apache License, Version 2.0 and is available online at http://daniel.ie