Please Help. My code doesnt work

HI everyone I am working on a battle system but its not working. I was supposed to start turn at 0(first character) and give him option to attack heal or try luck on instantly defeating enemy. once he chose, the second character plays and does the same once there is 2 they both take random damage. When I run the code The turn sets itself to 3, and nothing happens. Please Help. Thank you

Here is the code

// code

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class Battlesystem : MonoBehaviour { public float Turn = 2; public float currenthealth = 100; public float demage; public float heal; public float opponenthealt = 1000; public float DemageToOponent; public float Luck; public GameObject cube; public float currenthealth2 = 100; public float demage2;

 // Update is called once per frame
 void Update()
 {

     if(currenthealth <= 0)
     {
         Die();
     }
     if (currenthealth2 <= 0)
     {
         Diee();
     }
     //první postava

     if (Turn is 0)
     {


                          if (Input.GetKeyDown("space"));
                        {
                                 Turn = Turn + 1;
                        DemageToOponent = Random.Range(10, 30);
                        opponenthealt = opponenthealt = DemageToOponent;
                        }

                if (Input.GetKeyDown("left alt"));
                 {
                        
                        Turn = Turn + 1;
            
             if (currenthealth <= 80)

                        {
                                heal = 0;
                        }
                      if (currenthealth <= 80)

                      {
                              heal = 20;
                      }

                         if (currenthealth is 90)

                         {
                                   heal = 10;
                         }



                     currenthealth = currenthealth + heal;

                     

                 }

    
             if (Input.GetKeyDown("left ctrl"));
            {
             Luck = Random.Range(1, 31);

             Turn = Turn + 1;

               if(Luck is 10)
               {
                 Dieenemy();
               }


            }

     }

     if (Turn is 1)
         {






             if (Input.GetKeyDown("space")) ;
             {
                 Turn = Turn + 1;
                 DemageToOponent = Random.Range(10, 30);
                 opponenthealt = opponenthealt = DemageToOponent;
             }

             if (Input.GetKeyDown("left alt")) ;
             {

                 Turn = Turn + 1;

                 if (currenthealth2 > 80)

                 {
                     heal = 0;
                 }
                 if (currenthealth2 < 80)

                 {
                     heal = 20;
                 }

                 if (currenthealth2 is 90)

                 {
                     heal = 10;
                 }



                 currenthealth2 = currenthealth2 + heal;



             }


             if (Input.GetKeyDown("left ctrl")) ;
             {
                 Luck = Random.Range(1, 31);

                 Turn = Turn + 1;

                 if (Luck is 10)
                 {
                     Dieenemy();
                 }


             }

     }




     

     if(Turn is 2)
     {

         demage = Random.Range(10, 30);
         demage2 = Random.Range(10, 30);

         currenthealth = currenthealth - demage;
         currenthealth2 = currenthealth2 - demage2;

         Turn = Turn - 2;
     }

             void Dieenemy() {
             Destroy(cube);
           }
             void Die()
             {
                Destroy(cube);
             }
     void Diee()
     {
         Destroy(cube);
     }
 }

}