Depends are we talking about hard as Nails Gameplay or Glitchy as Hell with terrible Physics / control systems that make them impossible to finish.
Demon Souls,
Cauldron II,
Ghosts and Goblins,
Last Ninja 2,
R-Type,
Contra
Demon Souls,
Cauldron II,
Ghosts and Goblins,
Last Ninja 2,
R-Type,
Contra