using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {   

        string sourceString = "[[14,12,11,15],[4,3,6,6],[10,13,1,9],[12,4,11,15],[3,10,8,5]]";

        List<Score> resultScores = StringToScoreList(sourceString);

        Console.WriteLine("Result: " + ScoreListToString(resultScores));

        Console.WriteLine("Source: " + sourceString);

    }

    public static List<Score> StringToScoreList(string scoresString) {

        List<Score> resultScores = new List<Score>();

        if (!string.IsNullOrWhiteSpace(scoresString)) {

            string tmpString = scoresString.Replace("],[", ";");

            tmpString = tmpString.Replace("[[", "").Replace("]]", "");

​

            string[] scoreStrings = tmpString.Split(";");

            foreach (string scoreString in scoreStrings) {

                string[] entryStrings = scoreString.Split(",");

                Score score = new Score(entryStrings);

                resultScores.Add(score);

            }

        }

        return resultScores;

    }

    public static string ScoreListToString(List<Score> scores) {

        return "[" + string.Join(",", scores) + "]";

    }

    public class Score {

        int k1 = 0;

        int k2 = 0;

        int k3 = 0;

        int k4 = 0;

        public Score(int k1, int k2, int k3, int k4) {

            this.k1 = k1;

            this.k2 = k2;

            this.k3 = k3;

            this.k4 = k4;

        }

        public Score(string k1, string k2, string k3, string k4) : this(Convert.ToInt32(k1), Convert.ToInt32(k2), Convert.ToInt32(k3), Convert.ToInt32(k4)) {}

        public Score(string[] entries) : this(entries[0], entries[1], entries[2], entries[3]) {}

        public override string ToString() {

            return "[" + string.Join(',', new[] {k1, k2, k3, k4}) + "]";

        }

    }

}