We all know that a cramped position is bad. But where is the real danger, if there aren't good attacking lines aiming at the king? The brilliant Rashid Nyezhmetdinov shows us how to crack open the shell by opening up a file and using it as an invasion path to the 7th rank.
Under pressure, Black weakens his kingside and allows White to gain a permanent advantage in space. This is especially clear after about 26 moves. The advantage is clear, but technique is needed to earn the full point.