our 3rd go (has a nice menu and input cleaning, but not the quick exit stuff)

ListOfListOfInts

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static List<List<int>> generateLiveCells()
        {
            var allCoordinates = new List<List<int>>();
            var selectedOption = getSelectionFromMenu();
            if (selectedOption.Key == ConsoleKey.D1)
            {
                randomStartingCellPositionsCreator(allCoordinates);
            }
            else if (selectedOption.Key == ConsoleKey.D2)
            {
                Console.Clear();
                Console.WriteLine("Enter co ordinates of cells with X and Y values seperated by a comma, press s to finish!");
                Console.WriteLine("Press o to return to Options");

                var sNotPressed = true;
                while (sNotPressed)
                {
                    var inputKey = Console.ReadKey().KeyChar;
                    if (inputKey == 'o' || inputKey == 'O')
                    {
                        return generateLiveCells();
                    }
                    else if (inputKey == 's' || inputKey == 'S')
                    {
                        sNotPressed = false;
                    }
                    else
                    {
                        var inputValue = Console.ReadLine();
                        inputsParsedToPairs(allCoordinates, inputKey + inputValue);
                    }
                }
            }
            Console.Clear();
            return allCoordinates;
        }

        private static void inputsParsedToPairs(List<List<int>> allCoordinates, string inputValue)
        {
            var cleansedInput = new string(inputValue.Where(character => char.IsNumber(character) || character == ',').ToArray());

            var commaSeperatedInput = cleansedInput.Split(',');
            var xCoordinate = int.Parse(commaSeperatedInput[0]);
            var yCoordinate = int.Parse(commaSeperatedInput[1]);
            var coordinatePair = new List<int> { xCoordinate, yCoordinate };
            allCoordinates.Add(coordinatePair);
        }

        private static void randomStartingCellPositionsCreator(List<List<int>> allCoordinates)
        {
            var random = new Random();
            var numberOfLiveCells = random.Next(40, 50);

            for (var count = 0; count <= numberOfLiveCells; count++)
            {
                var yCoordinate = random.Next(25);
                var xCoordinate = random.Next(80);

                var coordinatePair = new List<int> { xCoordinate, yCoordinate };
                allCoordinates.Add(coordinatePair);
            }
        }

        private static ConsoleKeyInfo getSelectionFromMenu()
        {
            Console.Clear();
            var builder = new StringBuilder();
            builder.AppendLine("Welcome to the Game of Life!")
                   .AppendLine("Options")
                   .AppendLine("Press 1 for a randomly generated game")
                   .AppendLine("Press 2 to enter live cells");

            Console.WriteLine(builder);

            var selectedOption = Console.ReadKey();
            return selectedOption;
        }
        static void Main(string[] args)
        {
            Console.Clear();
            foreach (var item in generateLiveCells())
            {
                Console.SetCursorPosition(item[0], item[1]);
                Console.Write("X");
            }
            Console.ReadKey();
        }
    }
}