public Tuple<string, string> RejectChallenge(Guid challengeId)
{
var c = CloudWarsData.GetChallenge(challengeId);
var p1 = CloudWarsData.GetPlayer(c.Player1);
var p2 = CloudWarsData.GetPlayer(c.Player2);
CloudWarsData.RejectChallenge(challengeId);
return new Tuple<string, string>(p1.ClientId, p2.DisplayName);
}