private void Start()
{
if (roomSize < 2.5f)
{
throw new UnityException("room size is too small");
}
generator = new MazeGenerator(columns, rows);
generator.BuildInUnity(floorPrefab, wallPrefab, roomSize);
monstersContainer = new GameObject();
InitContainer();
// After 10 seconds, the game will spawn a monster every min
StartCoroutine(Spawn(10.0f, 60.0f));
}