you cant say Mass effect 3 if you didnt have that feeling of biggest disappointment half an hour before the ending. If you didnt then its your most disappointing ending. it was only 1-2 % of the entire game. its technically not possible to be biggest disappointment of the entire generation based off the ending

Also, Killzone 2.

Was promised an amazing experience, got a tedious crawl through the same dull grey industrial areas over and over, shooting the same dull enemies over and over, with the same dull WW2-eque guns.

Dodgy controls, terrible story/voice acting, fans didn't like the linearity. (I didn't mind the last, I find exploration incredibly overrated)

Open world games that allow you the freedom to ignore the story line and spend time doing what you want were far more rewarding than the scripted shooter and RPG game series that have popped up this generation.

GTA 4's its story line was too scripted just like a wannabe Hollywood B-Grade film. The fun part was going off and doing what you want ignoring the mobile phone calls and being a bad ass blowing things up, running away from the cops, hit and run, drive by shooting pedestrians just for the thrill of it. Shooting down police helicopters and trying to last as long as you can against the SWAT teams, military and police. You could also use the cheats to get the cars, ammo, guns you want and become invincible and spend hours creating havoc and killing anyone and anything that got in your way.

Oblivion and Skyrim are two great open world games where the story and its side quests can be done whenever you want. You go off exploring the world eliminating whatever stands in your way and helping yourself to loot robbing people's houses, pick pocketing sneaking around, assassinating unsuspecting targets, fighting and killing the guards and out running them.

Mass Effect 3 felt like a step down from Mass Effect 2. All the decisions and choices you made in the first two games counted for nothing in Mass Effect 3. Mass Effect 3 fell apart in the final third of the game and it was capped off with the same dull, lame, generic ending. For me: Mass Effect was an 8.5, Mass Effect 2 was a 9, Mass Effect 3 was only a 7.

Uncharted 2 POS MP

The orange box, honestly Half life sucks 

BF3 ( the entire game) 

Modern warfare 2.........the most overrated POS ive ever played and wasted 60 friggin bucks on. 

I can't believe people are putting Last of Us on this list. Also, I liked GTA IV. The control scheme and story were superior to San Andreas in my opinion, but oh well, I guess a lot of people didn't like it.

I personally was disappointed by Mario Kart Wii and Metroid Other M. Mario Kart Wii just wasn't as fun as any previous Mario Kart game, and Metroid Other M didn't feel like a Metroid game at all.

LA Noire.
AC3.

What are some of your favorite games this gen?  Just out of curiousity.

I thought both of those games were great. Although the connor character was a disapointment,but I loved messing aroung in the world. 

Herpes?

1. Spore. I has such high expectations of this game. The first part (till you get to build stuff) was completely and totally awesome. From that point on, I didn't even bother playing it.

2. Nier. Tried so many times to beat this game, but I always get bored and give up. Not believing you guys again.

3. Enslaved: Odysee to the west. Man was the this game awesome for the most part. Then it became repetitive. The combat is great, the characters are great, the voice acting is awesome. The enemies are uninspiring and I got bored quite a few times while playing it. Never managed to finish it.

I'm sure there are more, but these ones had tremendous potential, which was waste.

edit: Almost forgot the most important ones:

4. Wii sports. Such a great game for the first 15 hours and then it gets terrible. I'm glad Sports Champions improved upon it. Great concept by all means and the way I wish games and the game industry would head (I know les hardorez hate it though). 

5. WiiFit: Can't express how disappointed I was in this game. Don't know what I expected, but what I do know is that it was by all means a massive waste of money (paid more than 100 euro for it).