The Pop program was built using the Pop Framework classes for Rudy Rucker's textbook Software Engineering and Computer Games. Full source and executable for the Pop Framework are available from the book website www.rudyrucker.com/computergames
Normally developers build only one game at a time with the Pop Framework, but the Pop program includes nine games. Only four of these games are in a finished, playable state with a clear goal: Spacewar, PickNPop, Airhockey, and Defender3D. The others serve only to demonstrate features of the Pop Framework and to provide stubs for easy extension.
Since the Pop program is designed to let developers explore possibilities for their own games, there are more control options than one would want to have in a finished game.