-The first few levels of (Dark Forces III

Jedi Knight II: Jedi Outcast. The shooting was good in the other Dark Forces, but in this game it was just a pain in the ass. Only three guns (In the parts were you HAD to use guns that is. You got plenty more once you had a lightsaber, but you'd be using your freakin' lightsaber by then), way too hard, and pulled a bunch of bullshit suprise death sequences just to ruin your quicksave. The Sniper level once you get your lightsaber is also bullshit, you can get insta-killed from across the map by snipers with lightning reflexes.
-Killer Croc in Arkham Asylum. Boring, pointless rinse-and-repeat section.
-Oblivion Gates in Oblivion. Do the same dungeon over and over (There's 9 unique maps for Oblivion gates, 2 of them locked to story sections. Up to 60 Oblivion gates can pop up on the map) or have infinitely spawning demons attack you? Most of the main quest wasn't very good, but the Oblivion Gates were particularly horrible.
-Mass Effect 2's ending. No, really. Mass Effect 2's ending. 2's. Not 3's. Oh, don't get me wrong, the suicide mission was amazing, definitely my second favourite sequence in the ME series. It's the end boss that is so amazingly retarded it hurts. Also, the lack of a reasonable choice at the end ("WILLINGLY give incredibly valuable artifact to terrorist" vs "Blow up incredibly valuable artifact you've been trying to get all game")
-The entire main quest of Fallout 3. Even Liam Neeson couldn't save it.
-The railroad section of Half Life 1. People don't complain about this one, but holy crap do I personally find it annoying. Sitting in a cart for half an hour, doing nothing but pushing buttons. Also, Xen. I don't think I need to explain that second one.
Honorable mention to:
-The SUPER GRAVITY GUN sections of Half Life 2 and Ep 1 (AKA: Half of Ep 1). I like the plot going on during these sections. In both cases, what's happening with the characters and the world I extremely enjoy. But the gameplay is just so bloody dull. Run up to dude, pick up dude. Rinse and repeat for an hour or two. The rest of the games had gun variety and some sort of possibility you might die. This doesn't. Manages to gain the "Honorable mention" qualifier thanks to the aforementioned story going on in the background.
Captcha: half done. I don't know, I think my post is long enough as it is.