GameController_1.cs

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

public class GameController_1 : MonoBehaviour
{
    public GameObject hazard_1;
    public Vector2 spawnValues_1;
    public int hazardCount_1;
    public float spawnWait_1;
    public float startWait_1;
    public float waveWait_1;



    void Start()
    {
        StartCoroutine(SpawnWaves());
    }

    IEnumerator SpawnWaves()
    {
        yield return new WaitForSeconds(startWait_1);
        while (true)
        {
            for (int i = 0; i < hazardCount_1; i++)
            {
                Vector2 spawnPosition = new Vector2(Random.Range(-spawnValues_1.x, spawnValues_1.x), spawnValues_1.y);
                Quaternion spawnRotation = Quaternion.identity;
                Instantiate(hazard_1, spawnPosition, spawnRotation);
                yield return new WaitForSeconds(spawnWait_1);
            }
            yield return new WaitForSeconds(waveWait_1);
        }
    }

    //By level UFO Update
    void Update()
    {

        //level 1
        if (ScoreScript.scoreValue >= 100 && ScoreScript.scoreValue < 200)
        {
       
            hazardCount_1 = 2;
            spawnWait_1 = .70f;
            waveWait_1 = 10;
        }

        //level 2 
        if (ScoreScript.scoreValue >= 200 && ScoreScript.scoreValue < 300)
        {
            
            hazardCount_1 = 3;
            spawnWait_1 = .60f;
            waveWait_1 = 9;
        }

        //level 3
        if (ScoreScript.scoreValue >= 300 && ScoreScript.scoreValue < 400)
        {
            hazardCount_1 = 4;
            spawnWait_1 = .60f;
            waveWait_1 = 9;

        }

        // level 4
        if (ScoreScript.scoreValue >= 400 && ScoreScript.scoreValue < 500)
        {
           hazardCount_1 = 4;
            spawnWait_1 = .50f;
            waveWait_1 = 9;

        }

        //From level 5 and onwards
        if (ScoreScript.scoreValue >= 500 && ScoreScript.scoreValue < 1000000000)
        {
            hazardCount_1 = 5;
            spawnWait_1 = .50f;
            waveWait_1 = 8;
        }

        if (ScoreScript.scoreValue >= 600 && ScoreScript.scoreValue < 700)
        {
            hazardCount_1 = 5;
            spawnWait_1 = .50f;
            waveWait_1 = 7;
        }

        if (ScoreScript.scoreValue >= 700 && ScoreScript.scoreValue < 800)
        {
            hazardCount_1 = 6;
            spawnWait_1 = .50f;
            waveWait_1 = 7;
        }

        if (ScoreScript.scoreValue >= 800 && ScoreScript.scoreValue < 900)
        {
            hazardCount_1 = 6;
            spawnWait_1 = .45f;
            waveWait_1 = 6;
        }

        if (ScoreScript.scoreValue >= 900 )
        {
            hazardCount_1 = 7;
            spawnWait_1 = .40f;
            waveWait_1 = 7;
        }

    } 

 


}