Fallout 3 and Infamous. Also the 1st Uncharted.

Halo Combat Evolved
Splinter Cell
jet Set Radio Future
Hitman Constracts
Need for Speed Underground
Freedom Fighters
Oddworld Strangers Wraith
F.E.A.R.

Bioshock

Condemned

Mass Effect

Assassins Creed 2

Resistance 2

Crackdown

Split Second

Blur

Deus Ex Human Revolution

Far Cry 2

Dishonored

Far cry 3

Okami and Shadow of the Colossus.

Everything about them was epic. I would like to add Persona 3 and 4 as well as GTA SA.

Resistance 3,Heavy Rain, Uncharted 2, Little Big Planet, The Walking Dead. I did not expect much from these games until i played them.

My biggest upset this Gen has to be Spec Ops: The line. Amazing amazing amazing game. The story, the twists, the characters, even the gameplay (since I had heard that it was the weakest part of the game) It all worked perfectly to simply blow my mind. I recommend it to all story driven, FPS lovers.

The World Ends With You, Fire Emblem: Radiant Dawn, Monster Hunter Tri

I guess you should have titled it something like "games that unexpectedly blew you away" or "games you didnt expect to be blown away by" 

Its all good though because everybody knows what you ment..

Lol

Final Fantasy 12. I expected it to suck and resisted playing it many times... it didn't exactly 'blow me away', but it got me through a health crisis and I probably put way too many hours into it. It convinced me to finish FFX-2 and get the 100% too.

Deadly Premonition. I laughed back at how horrible and putrid the game looked and played. But bought it anyway (For a retail game, it was pretty cheap!) and became one of my fav of this generation.

Little kings story on the wii, I bought it because a friend of mine said it was a great game, the funny thing was that he was actually referring to a completely different game, I just heard him wrong. Good thing I did because it was probably one of my favorite games of last generation.

The Elder Scrolls: Skyrim

It was the first game that I had ever played from the series. My friends from work were talking about it and I said I would rent it and play five hours worth just to give it a try. I wasn't a big fan of RPG's at that time. So, I rented it and that first night I played more than five hours and I was hooked. It definitely blew my mind!!