Wim van Eck built this pacman game, where a human player can play against real crickets, for his graduation project.
In his project he build a Pacman game, in that the player can play Pacman against real crickets, that controls the ghosts in the Pacman maze. By doing this he analyzes the advantages and disadvantages of real-time behaviour of live animals in comparison to behavior-generating code in computer games.
Interesting about this idea in my opinion is, that through the use of real life elements in a game, the game gets unpredictable. It happens once to him that during playing the game one cricket piled his skin. Because of the new and white skin of the cricket, the color detecting system of the game could not detect the cricket for certain period. During this period the cricket was a real ghost for the system.
http://www.pixelsix.org/wiki/pmwiki.php/Blog/18-04-2006 - via Cynical-C
Update 7/17/06: Visit Wim's direct website: http://pong.hku.nl/~wim/bugman.htm