Ima have to say Super Mario Galaxy 2 and Red Dead Redemption

Super Mario Galaxy 2 and Monster Hunter Tri

For DLC I would say Cave Story

Didn't cave story come out like 5 years ago?

Heavy Rain:  Incredible graphics, unique interface, compelling story.  One of the most captivating games I've played this gen.

Alan Wake:  Some of the best graphics I've ever seen (at night--sorta average during the daytime scenes), thought provoking story, incredibly tense atmosphere.

Bayonetta:  Possibly the best action game of all time.  Gameplay perfected.  Best new character of the year.

Super Mario Galaxy 2:  Refined and polished like no other.  Pure gaming bliss.

Mass Effect 2:  Storyline that sucks you in, great graphics, all around great game.

God of War 3:  Haven't played it but the reviews can't be wrong.  It gives its audience what it wants.

All of these games (except GoW3 since I haven't played it, yet) get my highest recommendation.  It's hard to imagine a game in the next few months topping them.

Mass Effect 2, Red Dead Redemption, and uhhhh that's it. I've only bought 2 games released in 2010.

I only have Mass Effect 2 and Alan Wake on the short list so far. I'm looking forward to the second half of the year more though.

for me either,

Star ocean 4 last hope International edition

Final Fantasy 13

Bayonetta

My nominees.

Heavy Rain - I know this game is very divisive, but it made me play a video game in a way I never have. Never have I TRULY thought about how my actions affected the characters, being that usually it didnt matter much in the grand scheme. I know ME2 is the same way, but I havent played it yet as I just got my 360 back.

God Of War 3 - Epic finale in the trilogy. Not only did the story finish on a high note, but they actually improved the combat which I was worried about. Add the even more improved presentation and graphics, and you got the whole package.

Red Dead Redemption - After GTA4, I was verry worried I was falling for the hype machine again. Im glad I didnt talk myself out of buying this game. Excellent game, I love how Rockstar made John feel so....human. I actually liked the family missions and Bonnie missions the best, because he seemed like a normal guy during those as opposed to a invincible gunslinger.

Honorable mentions - FFXIII and Splinter Cell:Conviction. Very close, but not quite at those 3 games level IMO.

No question that Red Dead Redemption and Mass Effect 2 tower above the rest in quantity and quality. Still I hve missed a lot of good games like Alan Wake, Heavy Rain, and Super Mario Galaxy 2.

Mass Effect 2 - It took an already great formula and improved on it. I loved what they did with the gameplay, ammo, and the removal of the Mako. It had a great story, interesting characters and was just an amazing game.

I did miss Wrex though...

God of War 3 - God of War is the type of series where more of the same is a great thing. The word 'epic' is used far too loosely in gaming communities, but I think it aptly suits GOW3. Everything is just so large scale, the score so fitting that it makes me feel like I've accomplished something moreso than other great games. And Hell, it's incredibly fun.

Mario Galaxy 2 - Though I haven't started it yet, I'm assuming it's similar to its predecessor in fun factor; if it is, then it's an obvious candidate.

Honourable mention to FFXIII - Though I thought it's battle system to be the best in the series, it suffered from mostly disinteresting characters.

It really has been an astounding first half-year.