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

using UnityEngine;

public class GameManager : MonoBehaviour
{
    public static GameManager Instance;

    public bool IsBuildMode = false;
    private Tower selectedTower;
    public Tower SelectedTower { get { return selectedTower; } set {
        if (selectedTower != null)
            selectedTower.TowerSelected(false);

        selectedTower = value;
        selectedTower.TowerSelected(true);
    }}

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