Holiday pieces:
 Set the system date to December 25 for Christmas pieces, October 31
 for Halloween pieces, and July 4 for desert pieces.
 
 Ghost train:
 Set the Windows system clock to October 31 and watch for the ghost
 train. 
 
 Winter time:
 Press [Caps Lock] before playing a game.
 
 Create a big fountain:
 Place four fountains in a square to create a single large fountain.
 
 Space shuttle launch pad:
 Place two radar stations next to each other to create a space shuttle
 launch pad.
 
 Giant robot:
 Place a Large IG tower next to a radar station to get a giant robot.
 
 Loch Ness monster:
 Place a normal pond anywhere on the map. Then, place sunflowers
 surrounding the lake and Nessie will visit.