Gotta be Devil May Cry 4 SE Bloody Palace, clears with both Nero and Dante, no super costumes.
BP demands you fully master the combat system and are able to focus and execute near-flawlessly for a period of around two hours across 100 floors of enemy encounters.
You're working against a timer that refills when you clear floors, and to top it all off you have to fight Dante with AI limiters removed at the end- he uses everything in his arsenal and can just instantly delete you with a charged royal release if you're not watching for his defensive moves.
Doing it as Nero isn't too bad since his moveset is all fundamentals, but good lord doing it as Dante is ridiculous. You need to know the right moves to beat every enemy comp the game throws at you, which means using everything you have and being able to do all the mental sword, gun and style juggling as you fight.
It's pretty crazy.
Beating Bayonetta 1 on Infinite Climax Mode (without assists).
High five for that, Gracious and Glorious on that goddamn staircase were harder than any boss the game had to throw at you. Unlocking Jeanne was a great bonus as well.
Figuring out that I had to get some cereal and put it into a microwave in order to be able to go into space in Mad Professor Mariarti. This was pre-internet and no magazines had walkthroughs for a game that no fucker had ever heard of.
I mean, how else are you meant to make a nice warming bowl of porridge to survive the cold?
I should play that game again someday, I have a lot of nostalgia for it.
Ornstein and Smough Attorneys at law
That's gold. How have I never heard that one before