This video was great, it is an hour-long but it really shows you the workings of the amazing and free, Project Anarchy.
Hugh Johnson gives a great run through on how easy it is to make a video game in the software. Hugh runs through the physics, particles, meshes and even the skeletal animation software. It really does blow the pants off most game creation software.
Go to http://projectanarchy.com/ to give it a go.