Devil May Cry 4 - Trying to beat Dante Must Die mode with an S rank on every mission.
Devil May Cry 3: Special Edition - Still have yet to play through Hard mode as either Dante or Vergil, (just got both DMC3 and 4 for PC a few months ago) although for the time being, I'm focusing on DMC4.
Mega Man 9 - still have yet to clear some of the challenges (beat the game without taking ANY damage, beat the game 30 times, and beat the game 5 times in one day), however, I've surprisingly started to grow weary of the game. I just prefer the more stylish action and variety in the boss' attack patterns of the Mega Man X series.