void GroupUpdate()
    {
        if (IsStaying())//doesn't move
        {
            //Debug.Log("Next");
            playfield.UpdateField();

            Spawn();
        }
        else
        {
            //Debug.Log("convert");

            //convert old to false
            foreach (Vector2Int block in oldGroup)
            {
                playfield.Convert(block.x + oldOffset.x, block.y + oldOffset.y, false);
            }

            //convert new to true
            foreach (Vector2Int block in newGroup)
            {
                playfield.Convert(block.x + newOffset.x, block.y + newOffset.y, true);
            }

            newGroup.CopyTo(oldGroup, 0);
            oldOffset = newOffset;
        }
    }