I'm not sure if this has been done and I'm sorry if it has.
What's the hardest Game you've ever played and why?
Hardest game I ever played was Devil May Cry 3: Dante's Awakening Special edition on the Ps2. If you know a bit about the development of the game, they messed around with the modes a bit making each difficulty level FAR more difficult then the one before making it almost impossible to Take your skills on
" normal" and go right up to " medium". The Hardest difficulty of the game increased the enemies health by an insane amount along and Made it so no matter what, Dante Died in one hit. The Bosses Original Health were insane to begin with.
YouTube - Devil May Cry 3 - Mission 19 Dante Must Die SS Rank (part 2)

The Final Boss on the hardest mode...you can't be hit once and are forced to dodge 2 attacks that we're impossible to dodge in previous modes
YouTube - DMC 3 Special Edition Final Boss DMD SS No Damage