Bài tập lớn C#

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

namespace Test
{
    class Skill
    {
        private int _damage;
        private int _mp;
        private int _reArmor;
        private string _name;

        public int Damage { get => _damage; set => _damage = value; }
        public int Mp { get => _mp; set => _mp = value; }
        public int ReArmor { get => _reArmor; set => _reArmor = value; }
        public string Name { get => _name; set => _name = value; }

        public Skill()
        {

        }

        public Skill(string name,int damage, int mp, int rearmor)
        {
            Damage = damage;
            Name = name;
            Mp = mp;
            ReArmor = rearmor;
        }
        public void ShowInfoSKill()
        {
            Console.WriteLine(Name + "(mana = " + Mp + ", dame = " + Damage + ", reduce armor = " + ReArmor + ")");
        }
    }

    class Player
    {
        private string _name;
        private int _MP;
        private int _HP;
        private int _armor;
        private List<Skill> _SkillList;

        public string Name { get => _name; set => _name = value; }
        public int MP { get => _MP; set => _MP = value; }
        public int HP { get => _HP; set => _HP = value; }
        public int Armor { get => _armor; set => _armor = value; }
        public List<Skill> SkillList { get => _SkillList; set => _SkillList = value; }

        public Player()
        {

        }
        public Player(string name, int hp, int mp, int armor,List<Skill> skillList)
        {
            Name = name;
            HP = hp;
            MP = mp;
            Armor = armor;
            SkillList = skillList;
        }
        public void ShowInfoPlayer()
        {
            Console.WriteLine("HP: " + HP);
            Console.WriteLine("MP: " + MP);
            Console.WriteLine("Armor: " + Armor);
        }
        public void get_dame(Skill skill)
        {
            HP -= skill.Damage + Math.Max(0, Armor - skill.ReArmor);
        }
        public bool dead()
        {
            return HP <= 0;
        }
        public bool CheckMana(Skill skill)
        {
            return skill.Mp <= MP;
        }
        public void ShowAllSkill(List<Skill> SkillList)
        {
            for (int i = 0; i < SkillList.Count; i++)
            {
                Console.WriteLine("Skill thu " + i);
                SkillList[i].ShowInfoSKill();
            }
        }
        public Skill UseSKill()
        {
            int i;
            do
            {
                this.ShowAllSkill(SkillList);
                Console.WriteLine("choose skill");
                i = int.Parse(Console.ReadLine());
                if (CheckMana(SkillList[i]))
                {
                    MP -= SkillList[i].Mp;
                    return SkillList[i];
                }
                else
                {
                    i = -1;
                    Console.WriteLine("Not enough mana");
                }
            }
            while (i < 0 || i >= SkillList.Count);
            return null;
        }
    }
    class Monster
    {
        private string _name;
        private int _HP;
        private int _Armor;
        private List<Skill> sKillList;

        public int HP { get => _HP; set => _HP = value; }
        public int Armor { get => _Armor; set => _Armor = value; }
        internal List<Skill> SkillList { get => sKillList; set => sKillList = value; }
        public string Name { get => _name; set => _name = value; }

        public Monster()
        {

        }
        public Monster(string name,int hp,int mp, int armor,List<Skill> skilllist)
        {
            HP = hp;
            Armor = armor;
            SkillList = skilllist;
            Name = name;
        }

        public bool Dead()
        {
            return this.HP <= 0;
        }
        public void get_dame(Skill skill)
        {
            HP -= skill.Damage + Math.Max(0, this.Armor - skill.ReArmor);
        }
        public void ShowInfoMonster()
        {
            Console.WriteLine("HP:" + HP);
            Console.WriteLine("Armor: " + Armor);
        }
        public void ShowAllSkill(List<Skill> SkillList)
        {
            for (int i = 0; i < SkillList.Count; i++)
            {
                Console.WriteLine("Skill thu " + i);
                SkillList[i].ShowInfoSKill();
            }
        }
        public Skill UseSKill()
        {
            int i;
            do
            {
                this.ShowAllSkill(SkillList);
                Console.WriteLine("choose skill");
                i = int.Parse(Console.ReadLine());
                if (i == 0)
                {
                    return SkillList[i];
                }
            }
            while (i != 0);
            return null;
        }
    }
    class BattleField
    {
        private Player _a;
        private Monster _b;
        private bool _isPlayerTurn;

        public bool IsPlayerTurn { get => _isPlayerTurn; set => _isPlayerTurn = value; }
        internal Player A { get => _a; set => _a = value; }
        internal Monster B { get => _b; set => _b = value; }

        public BattleField()
        {

        }
        public BattleField(Player a, Monster b, bool isplayerturn)
        {
            A = a;
            B = b;
            IsPlayerTurn = isplayerturn;
        }
        public void ChangeTurn()
        {
            IsPlayerTurn = !IsPlayerTurn;
        }
        public string Winner()
        {
            if (A.dead())
            {
                return B.Name;
            }
            else if (B.Dead())
            {
                return A.Name;
            }
            return null;
        }
        public void ShowResult()
        {
            Console.WriteLine("Winner is " + Winner());
        }
        public void Fight()
        {
            while (A.HP > 0 && B.HP > 0)
            {
                if (IsPlayerTurn)
                {
                    Console.WriteLine("===================");
                    Console.WriteLine("Luot nguoi choi");
                    A.ShowInfoPlayer();
                    Console.WriteLine("===================");
                    B.get_dame(A.UseSKill());
                    Console.WriteLine("===================");
                    ChangeTurn();
                }
                else
                {
                    Console.WriteLine("===================");
                    Console.WriteLine("Luot quai vat");
                    B.ShowInfoMonster();
                    Console.WriteLine("===================");
                    A.get_dame(B.UseSKill());
                    Console.WriteLine("===================");
                    ChangeTurn();
                }
            }
            ShowResult();
        }
    }
    class RunMain
    {
        static void Main(string[] args)
        {
            Skill skill1 = new Skill("Danh chay", 30, 0, 0);
            Skill skill2 = new Skill("Ban ten", 100, 30, 10);
            Player a = new Player("Cung thu", 200, 150, 10,new List<Skill>{ skill1, skill2 });

            Skill skill3 = new Skill("Danh chay", 40, 0, 0);
            Skill skill4 = new Skill("Ban ten", 100, 50, 30);
            Player b = new Player("Hiep si", 150, 100, 20, new List<Skill> { skill3, skill4 });

            Skill skill5 = new Skill("Thoi lua", 30, 0, 0);
            Monster c = new Monster("Ho", 500,0, 20,new List<Skill> { skill5 });

            BattleField War = new BattleField(a, c, true);
            War.Fight();
            Console.ReadKey();
        }
    }
}