Bullet is a great physics engine. It's easy to use, and the documentation is really well written and easy to follow. It's also reasonably priced. The only thing I dislike about Bullet is that it doesn't support some of the more advanced features of other physics engines, such as the ability to have a single rigid body act as a single object with multiple parts. I am using Bullet for a number of different projects, and it has been a great asset to me. Bullet is easy to use, and the documentation