* @param detectives List of detectives still in the game.
* @return A winner if game is over, or <code>null</code> if nobody won during the initial phase.
*/
protected MessageUpdate startGame(List<Actor> phantoms, List<Actor> detective) throws ServerException {
logger.info("Initializing a new game");
MessageStart msgStart = new MessageStart(graph);
logger.debug("Sending message 'start' to the detectives");
detectiveClient.sendMessage(msgStart);
logger.trace("Message sent");