public void ChallengeAccepted(ChallengeAcceptedMessage message){
		Debug.Log ("CHALLENGE ACCEPTED!!! ");

		GSEnumerable<> accepted = message.Challenge.Accepted;
		GSEnumerable<var> accepted = message.Challenge.Accepted;
		GSEnumerable<PlayerDetails> accepted = message.Challenge.Accepted;
	
		GetData (message.Challenge.Challenger.Id, message.Challenge.ChallengeId, "accepted");

	}

 The documentation says,

 Use GSEnumerable<var> for C#, but unity will not let me use <var> as a data type.

GSEnumerable<var> accepted = challenge.Accepted; 
string challengeId = challenge.ChallengeId; 
string challengeMessage = challenge.ChallengeMessage; 
string challengeName = challenge.ChallengeName; 
GSEnumerable<var> challenged = challenge.Challenged; 
var challenger = challenge.Challenger; 
long? currency1Wager = challenge.Currency1Wager; 
long? currency2Wager = challenge.Currency2Wager; 
long? currency3Wager = challenge.Currency3Wager; 
long? currency4Wager = challenge.Currency4Wager; 
long? currency5Wager = challenge.Currency5Wager; 
long? currency6Wager = challenge.Currency6Wager; 
GSEnumerable<var> declined = challenge.Declined; 
DateTime? endDate = challenge.EndDate; 
DateTime? expiryDate = challenge.ExpiryDate; 
long? maxTurns = challenge.MaxTurns; 
string nextPlayer = challenge.NextPlayer; 
GSEnumerable<GSData> scriptData = challenge.ScriptData; 
string shortCode = challenge.ShortCode; 
DateTime? startDate = challenge.StartDate; 
string state = challenge.State; 
GSEnumerable<var> turnCount = challenge.TurnCount; 

 Then,

 Send the accepted GSEnumerable through a foreach loop and access the precious playerDetails.

GSData externalIds = playerDetail.ExternalIds; 
string id = playerDetail.Id; 
string name = playerDetail.Name; 

Anyone know how to access these precious playerDetails in Unity3d using C#?

Yes! Thank you, thats the key. It would have taken forever to find this on my own.