3DTD/Assets/Scripts/Manager/GameManager.cs

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

public class GameManager : MonoBehaviour
{
    public static GameManager Instance;

    public bool IsBuildMode = false;
    public Tower SelectedTower;

    private void Awake()
    {
        if (Instance != this)
            Destroy(Instance);
        Instance = this;
    }
}