public void Add(ISystem system)
{
if (ContainsSystem(system))
{
throw new InvalidOperationException($"System {system.GetType().Name} already added to game manager.");
}
_systems.Add(system);
_systems.Sort();
var drawableSystem = system as IDrawableSystem;
if (drawableSystem != null)
{
_drawableSystems.Add(drawableSystem);
_drawableSystems.Sort();
}
system.AddToGameManager(_gameManager);
SystemAdded?.Invoke(this, new SystemChangedEventArgs(system));
}