Connect 4 Online - Update

This is a brief summary about today’s update of Connect 4 Online, a multiplayer-enabled four-in-a-row game for Android phones. One major improvement is in the points / ranking system, especially in the case when the opponent leaves the game. For simplicity we are using a simplified ELO-rating system from chess to determine how many points the players win and loose.

Round-Time is set to 30 seconds now! If your opponent doesn’t move within 30 seconds, you can exit the game — for the opponent it counts as lost and you will neither win nor loose points.

Other updates include:

• Checking of a network connection before connecting (avoids force close in that case, but requires one more permission)
• Mapping Server: To make it easy to update the Python server, the clients first connect to a mapping server and receive an IP + Port for the real server instance
• Numerous small fixes and smaller updates :-)

I hope you guys enjoy it and let us know about your opinion! We promise to keep improving it then :-D

Here is the code to calculate the new ELO rating for both players:

// This function returns an array of two doubles
// [0] is the new rating for player A, [1] for player B
private double[] calcElo(int status, double RA, double RB) {
	// status: 0 = draw, 1 = player A won, 2 = player B won
	double QA = Math.pow(10, RA/400);
	double QB = Math.pow(10, RB/400);

	double k = 20;

	double EA = QA / (QA + QB);
	double EB = QB / (QA + QB);	    	

	double SA = 0.5; // draw
	double SB = 0.5; // draw
	if (status == 1) {
		SA = 1;
		SB = 0;
	} else if (status == 2) {
		SA = 0;
		SB = 1;
	}

	double[] res = new double[2];
	res[0] = RA + (k * (SA - EA));
	res[1] = RB + (k * (SB - EB));
	return res;
}