zumbi-game/Assets/Scripts/ZombieSpawnerLogic.cs

using System.Collections.Generic;
using UnityEngine;

public class ZombieSpawnerLogic : MonoBehaviour
{
    public GameObject Prefab;
    public byte CooldownSeconds = 5;
    public byte MaxSpawns = 5;

    private float _lastSpawn;
    private readonly List<GameObject> _spawns = new();

    void Start()
    {
        _lastSpawn = Time.time;
    }

    void FixedUpdate()
    {
        RemoveDestroyedZombies();
        AttemptZombieSpawn();
    }

    private void AttemptZombieSpawn()
    {
        if (Time.time - _lastSpawn < CooldownSeconds)
        {
            return;
        }

        if (_spawns.Count >= MaxSpawns)
        {
            Debug.Log("Cannot spawn zombie, capacity reached");
            return;
        }

        Debug.Log("Spawning zombie");
        var newZombie = Instantiate(Prefab, transform);
        _spawns.Add(newZombie);
        _lastSpawn = Time.time;
    }

    private void RemoveDestroyedZombies()
    {
        _spawns.RemoveAll(zombie => zombie == null);
    }
}