A fantastic pinball designer named Python Anghelo passed away recently.  Phython designed many fantastic machines and was full of energy and enthusiasm for life and pinball.  Prior to his death, Python had been saying for a while that the follow up to his Pinball Circus was going to be produced.  The only Pinball Circus machines that exist are prototypes as it never went into production.  

One of the prototypes can be played at the Pinball Hall of Fame in Las Vegas.
http://www.youtube.com/watch?v=UUHaMvELf6A 

 
The machine has the player work up through a series of tiered playfields.  Based on the step by step progress, the game is linear and it is said that it lacks replay value.  Python defended this accusation by saying that the prototypes did not contain all that he had intended to include in the machine.

A group called Circus Maximus Games has announced that they intend to release a version of Pinball Circus.  Their blog includes interesting photos of the process used in creating vacuum formed ramps.