Hide/show movements in a multiplayer game

I get a problem with the module that I’m actually working on.

It’s a module with two defined sides. I would like that players can play a multiplayer game, but they can hide their movements to opponent. And when every moves have been done, then each side show his moves to other side.

Is there a solution using “synchronize”? I can’t try it myself, because today I’m alone… So it’s difficult to create a multiplayer game alone!!!