14. Way Of The Master Ninja - Ninja Gaiden II
Tecmo's remastered half spin-off from the Dead or Alive series (although 2D NES 'Gaiden got there first) was one of the best games the studio ever put out -
until part three anyway. When the first game immediately established itself as having one of the most unforgiving first bosses of all time - not to mention a learning curve that went from a steep incline to a brick wall challenging you to overcome it - for part two the stakes were even higher for those that did so with ease. Enter the Way of the Master Ninja achievement, and a difficulty setting that although optional, if you did dive in would ask you to hone your skills essentially to as fast as the computer could process the enemies' attacks. NG was already brutal, but in forcing you to genuinely master every frame for every weapon, every enemy animation and all the subtleties of when to dodge, cancel out of attacks and retaliate, Ninja Gaiden 2 was the step-up that solidified its identity whilst also thoroughly putting off all but the most hardcore players.