Technical additions:

• Models of Toxins: Added more data on sarin gas dispersion (our first example), and completed concrete toxin classes.
  
  
• Models of Citizenry and Active Props: Tested toxin riders, and finished manipulable props.
  
  
• Interactions and Menus: Implemented submenus and enabled multi-person selection.
  
  
• Commands and AI: Added about five more commands and group behavior.