I don't care if they're easy, I still hate it when games do that. No exceptions. Arkham Asylum was just lucky it was good enough of a game that I didn't entirely hate it for it.

You hate them when they are about 1% of game it can almost ruin it for you? Man, that's hatred for something in a game if I ever saw something.

tutorials. I don;t like being forced into doing them

This

Fetch Quests

A boring story that the developers think are good. Seriously. If the story gets in the way of the game then it shouldn't be so prominent. A little story to explain is fine, like Torchlight, but it shouldn't try to focus on it.

Vanquish had this problem big time. And by story I mean "too many cutscenes that show stuff that is cooler than what you can actually do in the game"

Everybody has already said most of them, but one of the biggest problems of gameplay, is if they don't work, or if the camera is artificially blocking you/out of control.

lol, everything I was going to say is already here(and obviously some stuff I don't mind/care too)
but even so I vote in forced tutorials and stealth stages(in non stealth games) as the real worst of them all.

true endings locked behind new game+ modes. Especially when the main game isn't good enough to warrant being played twice.

Ok i don't know if this is a mechanic, but enemies that don't seem to be too phased by being shot. I don't know what to call it, but i nickname it Bullet Sponges. This game is the worst offender in my collection. Thank god Uncharted 3 doesn't have this problem so far.

QTE is my arch enemy. I don't mind it in heated situations but it makes absolutely no sense in cutscenes.

Cutscenes should be those moments you sit back and watch something really cool happening, not sudden death QTEs that kill you if you fail. I'm looking at you , Tomb Raider 2013. (Still a great game regardless of that though)

The only other thing would be stealth scenes that are badly implemented. These can work really well too though. (I love how Watch_Dogs handles these for example, plenty of choices and it isn't an instant game over if you are seen since you can try to get out of enemy sight)

Auto saving. I can never tell when a game saves or not cause I am use to having actual save points in games. Annoys the heck out of me cause I am afraid of stopping my game when I have to cause I dont know if it has saved or not.

Auto saving is nice when it only saves at set points. Like in Bravely Default. It only saves when you go through a door or or up stairs in a dungeon. And you can turn it off if you want.

While I never thought too much about it, and with most games it isn't a problem. Sometime this can be an issue, and quit the annoying one if done wrong. Arkham Asylum is an example of doing it wrong and what you're talking about. I had to repeat a number fights and stuff because I figured it would have saved, but nope, it didn't.

I figure I only dislike auto-saving in things like RPGs where certain secrets are miss-able forever. Actually, the mechanic I despise here are secrets that you can miss forever.

I also despise stealing in JRPG's. Especially ones where the best equipment requires stealing.

Forced repetition of any kind annoys me. I don't mind repetition if it's something like optional backtracking, but the moment I'm tired of it, I should be allowed to do something completely different.

Any sort of Time Management system, especially if there's a timer that ticks away at all times.

Being forced to replay an entire large section of a game (anything that lasts more than 20 minutes, I'd say) just for failing once.

In short, Majora's Mask is the Anti-Christ in my eyes.

Being forced to play mini-games that aren’t fun and have nothing to do with the rest of the game. Oh, you like exploring adventure games like Zelda? Well here, lets bring the story to a screeching halt so you can play an unavoidable rhythm game.

Button mashing in fighting games, as well as different inputs per character for special attacks.

Two of the reasons that Dragonball Z Budokai Tenkaichi 3 is a far better fighting game than most. Special attack controls are universal among all characters, and button mashing will get you creamed quickly.

Exactly my point. If there was a standard of auto saving like every time you go through a door or into a new screen for example that would be fine, but as Jaz007 has pointed out I have had to redo some things in games where I thought it auto saved only to discover no it didn't. I know that some games like Assassin's Creed III or Borderlands for example with have a little symbol pop up when it auto saves but most of the time I don't see those symbols cause either they are up in the corner of the screen where I normally don't look or they symbol blends into the background.

I would have to say escort missions, as the AI almost always tends to be terrible. You're an unarmed character, there's no reason for you to be charging head on into enemy hordes like you're Leeroy Jenkins! Either charging in, or they get stuck.

I'm also not exactly fond of forced stealth missions in an overly non stealth game. If you're going to make a stealth section, flesh it out a bit more. I didn't mind switching between non stealth and stealth in the Arkham games. Since the stealth was as much a part of the game as the non stealth, and wasn't tacked on.