John Allen's Timsaver (JATS) is a favorite of many model railroader.  Most of us try to incorporate it into out home layouts as a means of adding excitement to our layout.  John Allen, who died in 1973, was probably one of the most talented model railroaders of all time.
The Timesaver program I've written is based on the game that John Allen created.  It is designed to be played counting the time or counting the moves.  My version is based on moves.  The screen, on a Model 100, will appear something like this:
                       A t D
            /-g B      B g B
     A t-o-o-o-b C     C b E
          $Lo          D r C
      D rR-o-BT G      E R G
         E   F         F B F
                       G T A
Along the bottom of the screen it will tell you if the (L)ocomotive is moving or coupled to a car, and your total number of moves.
The three columns indicate:1st row-starting locations, 2nd row-which car, 3rd row-where that car needs to end up at.  Once all cars are spotted, the locomotive must return to it's starting position to qualify as being finished.
Every change in direction is considered as a move.  The game is different everytime and it can take from 30 minutes to 3 1/2 hours to play.
Since many model railroaders are also computer enthusists, perhaps some of you "armchair model railroaders" will enjoy JATS.