Bad parts in great games.

[Lateralus]

The first thing that came to mind, for me, was the elevator fight near the end of Prince of Persia: The Sands of Time. That was awful. Difficult and CHEAP. You're fighting on this confined elevator platform with continuously respawning enemies, some of which are able to knock you down with one hit. By the time the animation of you getting back up finishes, bam - you're knocked down again without the opportunity to retaliate. It took me SO MANY TRIES to get one lucky run and make it past that part.

 

[Opus131]

Bed of Chaos in the first Dark Souls. This goes to a larger issue where games put in that one encounter out of left field that goes against all the gameplay mechanics you had been learning up until that point. I feel that more could had been done to make this fight more interesting, but in the end it is just annoying even if you have mastered what to do.

Someone suggested they put that in there to mess up cheaters. Doubt it but it's an interesting hypothesis.