I copied this from the Vassal 3.1 User Guide
Playing on the VASSAL Server
games are played in real time on the VASSAL Server. You can start a new game on the Server, or you can
joi n an existing game.
Server games are played in Rooms, where each Room represents a different group of players running the same
module. A room is named by the player who starts it. Rooms can be locked for privacy and players can be ejected from a
room by the player who started it. Players in the same Room can communicate using the Chat window.
The Main Room is where players are placed who are running a particular module, but not joined to any particular room.
You cannot play in the Main Room—you must join a room in order to play a game.
To start a game on the Server,
1. In Module Manager, in the Module Library window, double-click the module you want to play. The Welcome Wizard opens.
2.In the Welcome Wizard, under Select play mode, choose Look for a game online, and then follow theother Wizard steps as the module requires.
3.Click Finish. Upon connection, the chat window will displayWelcome to the Vassal Server, the name andversion number of your selected module, and any extensions loaded.
4.In the module window, click the Connectbutton in the Toolbar. TheActive Gameswindow opens.
5.In the Active Games window, in New Game, type the name of the game you want to start (for example,Monday Night Battle.)
6.You are moved from the Main Room into the game room you just named. Other players can now join this new room.
To join a game on the Server,
1.In Module Manager, in the Module Library window, double - click the module you want to play. The Welcome Wizard opens.
2. In the Welcome Wizard, under Select play mode, choose Look for a game online, and then follow theother Wizard steps as the module requires.
3. On the Toolbar, click Connect.
4. On the right side of the screen, the Active Games window opens. The Active Games window displays the Main Room for the module, which is the default location for all players who are not currently in a game, the Vassal Server and any active game rooms under that. Only rooms running the current module are displayed. The number of players is displayed in parentheses.
5. Double-click the name of the game room you wish to join.
6. If prompted, enter the password for the room. (This password is generally different from your Vassal password.)
7.Right-click on the name of a player who has already begun a new game, then click Synchronize. You andthe selected player will be synchronized and the game play can begin.
Players in a Server game must be synchronized in order to see each otherʼs moves and interact. (If players are not synchronized, then typically, each player will be able to move his pieces around the board, but the other players will not see any movement.) Players should pick a single player to synchronize with, such as the player who initiated the game. This will make sure that everyoneʼs game position is consistent. When you synchronize, any side selection, piece movement and
map selections you have performed will be reset and replaced with the game information of the player you synchronized to