by function map, do you mean map editor? How does multiplayer work?
Function Map shows you the part of the field that you have already passed. It helps you from hard situations (like when traps are all around you), or it gives you better survey of the field.
Multiplayer has two versions:
1) Via LAN/Internet: Faster player wins
2) 2 players on 1 PC: The first player goes down from the top and the second goes up from bottom. Players take turns after every move.
Thanks for Your interest!