Metroid Prime 3: Corruption
I always go back to this game. Even if I do prefer Echoes. The control scheme made this game, and Retro did what they did best which was wrap a whole game around a single cohesive idea.
It wasn't perfect, a fair amount of the gimmicky controls for certain puzzles didn't work quite as it should. But 90% of the time this game controlled like a pure dream and unlike anything else available at this time.
Top that off with just a great overall Metroid game that streamlined things a bit. Epic music combined with astounding boss battles that somehow glued everything you could do with a First Person IR controlled game into a tense and beautiful fight for survival.
Halo 3
Bungie really nailed this one. Sure the graphics weren't quite as good as they could have been (they were still pretty though). But man, they hit almost all the notes on this.
The amount of content, updates, just everything. It was a never ending thrill ride up until the end. And even now you can still hop on and have some fun thanks to MCC.
Definitely the best online multiplayer game of the generation, with bad ass completely co-op campaign to boot. What FPS games of today's world still struggle to understand.
You can have it all, if you try.
John Woo's Stranglehold
Max Payne meets Hard Boiled. The game was a pure adrenaline rush from start to finish. Midway's Swan Song, it's a shame we don't have a remaster.
The slo mo and destruction effects were straight up jaw dropping for the time.
EXCITE TRUCK
Take your Gran Tursimo, and throw that shit off a fucking mountain while jamming to the cheesiest rock tunes ever created.
This game is glory to the old days, blended with the satisfaction of tilting a Wii Remote and holding onto dear life. A complete and utter launch surprise, and one of my favorite racing games of all time.
The Elder Scrolls IV: Oblivion
This. This was the game that first screamed. Hey, Next-Gen is here. It was such a quantum leap compared Morrowind. The quests, the freedom. Everything, it absorbed me and my friends.
Definitely not perfect, had plenty of issues. But it was a total blast of a game. The Dark Brotherhood quests, so good.
Wii Sports / Wii Sports Resort
I know these are 2 games. But I see them as one. And they are, legitimate fucking classics. True multiplayer fun, and Resort actually had a lot of cool stuff to do on your own to boot.
The Legend of Zelda: Twilight Princess
Fuck the haters. The n00bs. The whiney bitches. This is the greatest ZELDA ever created. Its only weakness at the time was that it was too damn easy. Besides that, its a literal gift from the gods. A tour de force. A real, absolute, LEGEND of a game.
Street Fighter IV
Total arcade fighting fun. Just damn near perfect. A beautiful simple game, Capcom's finest game of the generation.
Ace Attorney Trilogy
Another set of games, I see as one and part of the generation. Mesmerizing, impossible to put down. Loved them all, and they felt so right at home on the DS.
Red Steel 2
It's really hard to not put Mario Galaxy here... But Red Steel 2 deserves to be mentioned. It will likely never get a sequel, or the credit it deserves. The controls in this game were so much fun, it was like Devil May Cry with your hands man.
The level design could be better, and there could have been a little more variety... But dammit this game was so much fun to play. And it was without doubt, the one game that lived up to that original trailer Nintendo first showed when announcing the Wii.