File | Start or Restart Game starts the animation of the game. If the game has already been run once, this control re-initializes the game and resets the player.
The File | New Game Window control creates a default Spacewar game.
The Open..., Save and Save As... opens or saves all of the currently active Pop game, critter, and sprite information. The Pop Framework does not save or reload the particular View menu settings such as viewpoint, view direction, using solid or wireframe sprites, using a background bitmap, etc.
A somewhat annoying feature of the Pop Framework is that you can’t open a given file if a file of the same name is already open. So if you have saved a file as test.p20 ...