Most of Fallout 3 =/ Didn't seem to have the same adventurous feeling I got from Oblivion.

Halo & Far Cry - The flood and the mutants put a damper on both games for me.
Spore - Getting to the creature stage and realizing I've been duped into buying a game designed for 7 year olds.
Oblivion - Finding out how repetitive the main quest is.
Startopia - Doing a search on Muckyfoot to see what other great games they've made...only to find out they're long dead.
OoT - Include me in the OoT is average at best camp. Any game that requires a faq to solve what should be a simple puzzles is bad in my books.

Which one did you prefer

Homefront.

Started fine ended with a big stop and then some credits. Short as well and the story was rubbish.

Playing TW2 is definitely it. I don't usually have high expectations for a game. So, I'm rarely disappointed. However, my expectations for TW2 were pretty high. The part of TW2 where my expectations were the lowest was, ironically, the point of my greatest disappointment. To be precise, it was the interface that killed my interest in the game and lost a vast amount of my respect for CDP as a whole. I know, the interface for TW1 was fairly terrible and was downright broken before the EE patch. Yet, somehow TW2 managed to be substantially worse than TW1 ever was. My biggest pet peeve for any game is having a broken or otherwise intolerable interface. You could have the greatest game in the universe but, if the interface is about as fun as rolling your fist in a mix of glue, sand, fiberglass and glass shards and then trying to shove it up your own ass, then I'm not going to want to play your game, ever.

It didn't help that TW2 was built like a cheap console port. The lack of support for 16:10 resolutions was a pretty big slap in the face but the complete inability to customize your controls was down right damning. To make matters worse, the interface failed on both fronts. It failed for keyboard + mouse and it failed for using a controller. The thing that just smacks of stupidity though is the inability to combine the use of your keyboard + mouse with a controller. There are times when using a keyboard + mouse are more convenient and times when a controller is more convenient but, to switch between them, you have to restart the game. Whoever designed the interface for TW1 deserves to be banned from ever working on another video game but whoever designed the interface for TW2 deserves to be burned at the stake (or worse if it's the same person for both).

Of all the problems with TW2, the one problem I couldn't ignore was the interface. It bothered me so much that, to this day, I've yet to play the game past the starting area. Even if the interface were fixed by a combination of patches and mods, I've lost so much interest in the game that I'm not sure I'll ever want to play it again. I have a strict rule against pre-ordering anything, a rule I broke for TW2. I wont be making exceptions to that rule ever again.

Some endings of RPGs that I liked playing and then in the end you defeat the final boss and that's it. :/

Deus Ex 2, realizing after 30 mins of gaming that I'm not having fun at all and there's no immersion whatsoever for me.
Later tried again and got 20 mins into it. Don't think I'll try again.

Witcher 2. Expected much, and then realized I'm playing some diablo clone, whacking 200 guards running down some pipe. Then Running another pipe in a dungeon. :(
This.. I'll give another go once the enchanced edition. Hope I'll break the 1hr mark this time.

The ending of Borderlands, I was enjoying myself and I regret it ended on such a low note.

Dungeons was the worst waste of my money, ever. Oh, but it came with this extra game, it might still be ok, my £30 might not be totally wasted. It troll faced me and refused to work on my computer.

Dragon Age 2 - when you realize that it's completely irrelevant who you choose to support in the Templar-Mage-conflict

Bioshock - after the twist, you know you have seen the best that game has to offer

The Legend of Zelda: Skyward Sword, LoZ: Spirit Tracks
What happened to the Zelda series? Is there any reason to make every Zelda worse than the previous one? And why do they fuck up the better Zeldas now (like on DS) by some stupid minigames as well?

Scribblenauts
Sure, the amount of items is impressive, but not so much if the levels mostly require specific ways of solving them.

Super Mario Galaxy 2
It was more of the same, only less impressive then and with more dumb minigames. Didn't even finish the second galaxy.

Secret of Mana
The fact that it was actually over at some point...

Arcadia, Bad Rats, Droplitz, Magnetis and probably many mroe
Totally not fun.

GemCraft Labyrinth
Sure, it was some improvement and the price of 5 dollars for the unlocks might be ok, but what happened to the shitload of gamemodes in Gemcraft chapter 0? And why did they dumb down the experience gaining system? They should have added the original modes (not only half of them) and made it combinable as well. Like: Killing arcane monsters all the time, etc.

Children of the Nile
I expected a Pharaoh clone in 3D but it is... well... too different and in bad ways.

GOG.com
Being unable to release Pharaoh Gold or Settlers 3 / Settlers 4 Gold after such a long time of having the publisher signed up. Weak!

Playing Dragon Age II (on PC) and realizing in horror that BioWare had managed to completely ruin the only franchise they had going that actually reminded me of the great CRPG's they produced in the late 90's and early 00's.

I love Mass Effect for what it is, and I respect it for being consistent and true to its genre -- when you pick up a ME game you know exactly what you're in for -- but I still haven't gotten over what Bio did to Dragon Age.

Indeed, I had a similar experience with Caesar IV.

Civilization 5

I've expected another leap in complexity and graphics (like from three to four). I actually ignored reviews because I thought. "It's Civilization, what could they possibly do wrong...".

Pretty much actually.

OF

I had NHL 09 on XBox. It was awesome. And then EA pulled the plug on multiplayer a few months after I got it. And I had it so I could play it with my bro 600 miles away.They didn't even give a patch to make peer-to-peer games or anything. I haven't purchased another EA game -- nor will I ever.

For NWN -- it's a great game. The single player is only okay. But the multiplayer was awesome. And there's some fantastic single player user-made campaigns.