nah.... a speedrun on very hard difficulty takes ~4hours
i plat this game end of december.
at first it was very frustating. I played on
normal difficulty and it was definitely not normal... If an enemy hits you, you are dead. The most hits you can survive are 2 or 3 and the checkpoints are unfair.
e.g. you fight in an arena with 4 waves of 3-5 enemies. every enemy can 1 or 2hit kill you. after finally finishing this "arena" you move on, survive 3 more areas with enemies and then die from a ranged 1-hit-attack. The checkpoint sends you back
before the arena with the waves of enemies.
I hated the game on my first playthrough. But then I started another playthrough on hard and very hard (afterwards) and enjoyed it more and more.
Since enemies 1hit you anyway, there is no real difference between the difficulties. and the road to victory is skipping all skippable enemies (surprisingly a lot) and rushing into battles. Never play defensive and try to avoid something at the beginning of a battle, just rush in an area and bash the attack button, knack is faster and has more range than almost all enemies. ranged enemies are still unfair to deal with, since while you evade one attack another one kills you, so safest bet is to use super powers ( preferrable O + △
.
grinding for diamond knack is a pain in the ass, though....