Game Falling Rocks (Not Fully Completed!)

namespace _12.FallingRocks
{
    using System;
    using System.Collections.Generic;
    using System.Threading;

    public struct Object
    {
        public int PosX;
        public int PosY;
        public string Str;
        public ConsoleColor Color;
    }

    public class GameFallingRocks
    {
        private const int HEIGHT = 25;
        private const int WIDTH = 43;

        private static Random randomGen = new Random();
        private static char[] symbs = { '^', '@', '*', '&', '+', '%', '$', '#', '!', '.', ';', '-' };

        public static void Main(string[] args)
        {
            checked
            {
                // Remove buffer and defining sizes of the console window!
                Console.BufferHeight = Console.WindowHeight = HEIGHT;
                Console.BufferWidth = Console.WindowWidth = WIDTH;

                // Defining size of playfield area:
                int playfieldWidth = 23;

                // Create the Dwarf:
                Object dwarf = new Object();
                dwarf.PosX = playfieldWidth / 2;
                dwarf.PosY = Console.WindowHeight - 1;
                dwarf.Str = "(0)";
                dwarf.Color = ConsoleColor.Yellow;

                List<Object> rocks = new List<Object>();
                int livesCount = 10;

                while (livesCount > 0)
                {
                    // Create a next Rock on random Top position:
                    Object nextRock = new Object();
                    nextRock.PosX = randomGen.Next(0, playfieldWidth);
                    nextRock.PosY = 0;
                    nextRock.Str = GetRockRandomSymbol();
                    nextRock.Color = GetRandomConsoleColor();
                    rocks.Add(nextRock);

                    // Move Dwarf (keys pressed)!
                    if (Console.KeyAvailable)
                    {
                        ConsoleKeyInfo pressedKey = Console.ReadKey(true);
                        while (Console.KeyAvailable)
                        {
                            Console.ReadKey();
                        }

                        if (pressedKey.Key == ConsoleKey.LeftArrow)
                        {
                            if (dwarf.PosX - 1 >= 0)
                            {
                                dwarf.PosX--;
                            }
                        }
                        else if (pressedKey.Key == ConsoleKey.RightArrow)
                        {
                            if (dwarf.PosX + 1 < playfieldWidth)
                            {
                                dwarf.PosX++;
                            }
                        }
                    }

                    // Moving Rocks!
                    // Needs to Create a new List of Rocks
                    List<Object> newRockList = new List<Object>();
                    for (int i = 0; i < rocks.Count; i++)
                    {
                        Object oldRock = rocks[i];
                        Object newRock = new Object();
                        newRock.PosX = oldRock.PosX;
                        newRock.PosY = oldRock.PosY + 1;
                        newRock.Str = oldRock.Str;
                        newRock.Color = oldRock.Color;

                        // Check if Rocks are hitting Dwarf!
                        for (int j = 0; j < newRock.Str.Length; j++)
                        {
                            if ((newRock.PosX + j == dwarf.PosX || newRock.PosX + j == dwarf.PosX + 1 || newRock.PosX + j == dwarf.PosX + 2) && newRock.PosY == dwarf.PosY)
                            {
                                livesCount--;
                            }
                        }

                        if (newRock.PosY < Console.WindowHeight)
                        {
                            newRockList.Add(newRock);
                        }
                    }

                    rocks = newRockList;

                    // Clear the console!
                    Console.Clear();

                    // Redraw playfield!
                    PrintStringOnPosition(dwarf.PosX, dwarf.PosY, dwarf.Str, dwarf.Color);
                    foreach (Object rock in rocks)
                    {
                        PrintStringOnPosition(rock.PosX, rock.PosY, rock.Str, rock.Color);
                    }

                    // Print info!
                    PrintStringOnPosition(27, 8, "Lives: " + livesCount, ConsoleColor.White);
                    if (livesCount <= 0)
                    {
                        PrintStringOnPosition(27, 10, "GAME OVER !!!", ConsoleColor.Red);
                    }

                    // Slow down program!
                    Thread.Sleep(150);
                }
            }
        }

        private static string GetRockRandomSymbol()
        {
            int lengthSymbol = randomGen.Next(1, 4);
            string symbol = string.Empty;
            for (int i = 0; i < lengthSymbol; i++)
            {
                int index = randomGen.Next(0, symbs.Length);
                symbol += symbs[index];
            }

            return symbol;
        }

        private static ConsoleColor GetRandomConsoleColor()
        {
            var consoleColors = Enum.GetValues(typeof(ConsoleColor));
            return (ConsoleColor)consoleColors.GetValue(randomGen.Next(consoleColors.Length));
        }

        private static void PrintStringOnPosition(int x, int y, string str, ConsoleColor color = ConsoleColor.Gray)
        {
            checked
            {
                Console.SetCursorPosition(x, y);
                Console.ForegroundColor = color;
                Console.Write(str);
            }
        }
    }
}