Automatic Update Of Workbook

What I'd like to have is one workbook, that 2 people can open and both people will see all changes that happen to the workbook.

As an example, there would be a Player 1 sheet and a Player 2 sheet. When you open the workbook you choose which Player you are and then it defaults to your sheet. You can then place your ships and start the game.

Each player would take it in turns to guess a square on the opponents board and then this selection would be sent to the other players sheet and updated automatically.

Most of it I think is quite easy to do - the only tough part being the updating process. Could I do it as 2 workbooks one for each player, (password protected to stop cheating!) and then when a move is made both workbooks are closed, the change is made and saved and the workbooks are re-opened?