Make use of room variables to keep track of which players have arrived.
Using the sendMove() method of the ElectroServerAS object, you can easily send information to your opponent.
The sendMove() function allows you to send objects. It is a good idea to use a property like type on the object, to concisely describe why the object is being sent. For instance, in checkers you might have a special move for making a checker a king. In this case the type property would be "king". For other moves it would probably just be "move".
There are two characters used in this game, automatically chosen based on which player you are.
The world.char reference is used to point to the character whose turn it is.
The fall() function determines if a character is on a tile. If this is the case, the function tells the character to fall, and the game is over.