Metal Gear Solid 4: Guns of the Patriots
possibly, in fact no definitely the best game i have ever played, from the very start it didn't fail to disappoint at any point and it got even better with the scene at the end of Act 3 when Liquid is just destroying everything with his hands. Before this game i hadn't really played MGS before but i did after it and MGS2 was awesome aswel.

Final Fantasy XIII
i, unlike many others, wasn't expecting that much as FFX-2 and FFXII were slightly disappointing to me but it was a very pleasant surprise, battle system superb, graphics superb.

MGS4, hands down without a doubt.

Chaos Rings for the iPhone... so much quality... even the NY times wrote a review for it: http://www.nytimes.com/2010/04/24/arts/television/24chaos.html

I guess I have a few games that have really wowed me so far this gen.

Heavy Rain: I was a little skeptical if I would really enjoy this game but decided to try it out anyways. I'm playing through it right now and I must say I'm kind of shocked at how much I'm enjoying this. It looks amazing, the story is very interesting and the gameplay is quite unique. Despite it being QTE's, I get a rush whenever I'm fighting to stay alive wich you don't get from too many games. The uniqueness of this game has shocked me.

Demon's Souls: The difficulty shocked me. Plain and simple. I knew it was going to be hard but you don't really know until you finally start playing. Which makes everything you accomplish feel all the more rewarding. I know when I first went up against the Tower Knight and saw how big he was, I just stood there and thought "Wtf should I do?".

Valkryia Chronicles: How they combined strategy, action and TPS into the battle system surprised me. The artstyle, gameplay and how the story was told was all very fresh and unique to me.

NHL 09: The game that has shocked me the most probably. I've been playing NHL since 94 and every year it's the same thing. Update the roster, improve the graphics and add some small gameplay enhancements. I didn't like NHL 08 since it was still in the gameplay transition from the old style to the new style. Then NHL 09 got it perfect and completly changed the series all for the better. Made it so much more realistic and overall enjoyable. I guess what really shocked me was how EA stepped up and made some drastic changes to th series when they didn't have to. And it paid off, it got great reviews and a bunch of rewards for sports game of the year.

I suppose those are the four that stood out the most for me. Uncharted, MGS4 and CoD4 all shocked me to some extent as well.

I'll split into different departments as apart from Oblivion & Yakuza 3 no one game has actually surpassed my expectations on all levels as I knew my most hyped ones were gonna be amazing:

Graphics -- Uncharted 2

Gameplay -- MGS4 & FFXIII....both made a departure from the usual and both had the best combat systems in their respective franchises....this was a true surprise as especially FFXIII's paradigm system sounded like a gimmick when revealed, but it worked so amazingly! Didn't expect that much from the gameplay of both those beloved games of mine....but in the end its the gameplay of those games that made them shine the most for me, not their story shockingly. (more in FF13's case than MGS4)

Content -- Elder Scrolls IV: Oblivion, Yakuza 3, LittleBigPlanet

Story -- DQV (expected a cliched boring JRPG story...got a charming, epic and a wonderful Tale), Shin Megami Tense Devil Survivor (WOW at the story....after the boring Persona 4 I was afraid of going into it but it was so better sotrywise than Persona and amazed me a lot in that department)

Others are Super Mario Galaxy (sunshine was bad wasn't expecting much), Phoenix Wright Series (Can I say WOW...expected boring anime type game got a all round excellent game) on DS

flOwer (Visuals)
Uncharted (Arrival of the Spanish)
Uncharted 2 (Visuals/over the top set pieces)
Heavy Rain (Break from normality)
Valkyria Chronicels (Sheer Awesomeness)

1st time i played project gotham racing 3 and fight night r3 literally shocked me, they looked and played superb.

untill now, the visuals of gow3 are shockingly good, the forge section of game is utterly amazing.

but then theres shockingly bad also, the control on wii on core titles really put me off, i hope MH3 paves way for more games to have standard control support.

Oblivion - just the scope of the world and the depth of the creation.
GTA IV - not my cup of tea as a game, but the city it creates really is a marvel
Uncharted - really nailed having a decent B movie and characters plus it had some great set pieces
Little Big Planet - I didn't think it would deliver on the promise of creation, which of course it did in spades - also for me the best art direction so far. I love the look and the graphics of this game above all others this gen so far.

Uncharted DF, Gears Of War, Bioshock, Viva Pinata (so cute), Forza 3, Assassins Creed 2

Fire emblem RD shocked me. I had never played a fire emblem before. I was used to shining force and advance wars. Best purchase I ever made.