So I will preface this saying it was very difficult to pick the top 10. Anytime I make a list like this I can't help but think of all the things it leaves out. To help myself narrow it down I decided to focus on the overall experience I had with a game. They are not in any particular order, except maybe the oder I thought of them in.
1) The Legend of Zelda: Ocarina of Time (Nintendo 64)
This may well be my favorite game of all time. I don't even know how many times I have played through it, maybe a dozen? When you consider the games takes something like 15 hours to complete (going fast) that is quite a lot. Of course the first time was the best, back when the world of Hyrule was a new place and I had never met Gorons or Zoras and didn't know what would happen when I pulled the Master Sword out of the stone or who Sheik really was. Even though I think Majora's Mask is a stronger game, nothing can ever match that feeling I got the first time I entered Zora's domain or the Spirit Temple. This game is pure magic.
2) Super Mario 64 (Nintendo 64)
I didn't have a Nintendo 64 until I got one for Christmas with Zelda. Even after that I never owned Mario 64 until I recently bought it on virtual console for my Wii. However, that didn't stop me from playing Mario 64. I remember playing this in kiosks at blockbuster and the mall. I rented a Nintendo 64 and this game for a weekend maybe 3 times back when it was first out. I played it at neighbor's and friend's houses and I got every star. Even now I can tell you what each of the 15 secret stars are from memory and if pushed I could probably tell you how to get every single star. Mayhe not some from the later levels, but the first half I could play in my sleep. I probably do sometimes.
3) StarCraft (PC)
StarCraft dominated my life for a couple years. I mean I can't even begin to tabulate how many hours I put into that game. Hours and hours playing over LAN or over modem or over battlenet with Adam, Jeremy, Carlos, Than, and my other gamer friends. And that's just the multiplayer. The single player campaign also contained many hours of fun. And then there was the map editor and all the player-made campaigns and maps I played. Not to mention the maps I made alone or with Jeremy. Mmm... StarCraft.
4) Sonic the Hedgehog 2 (Sega Genesis)
This was my first game for genesis and I loved it. The single player game is possibly the single best sonic game ever. All those wonderful Zones,: Casino Night, Mystic Cavern, Metropolis... And J-P and I played the hell out of the 2 player competition. He was always Sonic and I was always Tails and it was always fun.
5) Mario Kart Double Dash (GameCube)
Super Mario 64's battle mode is better, but Double Dash's multiplayer races are not only the most fun of the Mario KArt series but some of the best multiplayer fun to be had in any game ever. It's simple enough that almost anyone can play it and the zany items ensure that they can occasionally win as well. Linking up 2 gamecubes in the Shorey House longue so we could play 8 player was worth every penny Alex (and I to a lesser extent) spent to make it happen. Even though the other TV was crappy and Vik always came in dead last it was pure gold. "Hi, I'm Daisy!" (Oh man, I just remembered we made a list where we assigned a person from the house to all the characters in the game. Who was I? Birdo?)
6) Wii Sports/Mii Channel (Wii)
The great thing about Wii sports is that anyone with a hand can play it. It's just a ton of fun. I'd say 40% of this fun is seeing a little person who looks like you run around. Helping people make their first mii and then getting them to play tennis or bowling is one of my favorite things to do on the Wii.
7) Smash Brothers Melee (GameCube)
First of all the idea of different Nintendo beating each other up is amazing. Second of all this is the only fighting game I have ever been any good at. Third I can't even tell you how many marathon sessions of this I played with Adam, Jeeremy and Ben. 99 Stock is a rEdiculous way to play. Even though Adam completely pwned me at this game at least in this version I had annoying taunts to utilize annoy him. Peach's "Sweet!" and Game and Watch's bell made me feel like I had at least had a moral(?) victory.
8) Metroid Prime (GameCube)
One fo the most immersive, atmospheric games I have ever played. The only first person shooter I am worth a damn at. While the later games in the series have had various improvements, none of them match the experience of this game. Going through that downed, partially sunken frigate is one of the best moments in all of videogaming history. It's a beautiful game and it has some of my favorite bosses in any game. I've played through it 4 times already, and probably will a few more times.
9) Chibi Robo (GameCube)
By now I've played through over a dozen games with Stephanie. Some of them it was the first time I ever played through, others it was the latest of many play throughs. But this game more than any other is inextricably tied to her. I played very small portions of it without her (parts she had no interest in) but otherwise I've only played it with her and I can't imagine it any other way. It's also an amazing game in it's own right. Cleaning has never been so much fun or so rewarding. You play a tiny little robots whose goal is to make others happy. You even earn happy points.
10) Star Wars Rogue Squadron III: Rebel Strike (GameCube)
The best part about this game is that it includes Rogue Squadron II: Rogue Leader playable as 2 player Co-Op. This means that you can play through all the important space battles of the original star wars trilogy with a wingman. Playing the Battle of Endor with him in and A-wing and me in a B-wing was sweeter than words can say. I don't own this game, but I don't really need to because the Adam and Alex already have it.
Here are some of my favorite games that didn't make the cut:
Super Mario World (SNES)
Chrono Trigger (SNES)
Sonic 3 & Knuckles (Sega Genesis)
We Love Katamari (PS2)
Shadow of the Colossus (PS2)
Majora's Mask (Nintendo 64)
Jet Force Gemini (Nintendo 64)
Eternal Darkness (GameCube)
F-Zero GX (GameCube)
Pikmin 2 (GameCube)