I am very strict with my scores, to me it isn't an easy task for a game to get an 8 or higher. It must be very good.
Going by how I have rated games here on VGC (in the game collection in my profile), I only gave one (1) game ever a 10/10. That game is Legend of Zelda: Ocarina of Time. I gave a couple a 9.5/10 or 9/10, but getting above 9 is extremely rare to me, because a game needs to be near perfect for me and my personal tastes. For all intends and purpose, the games I rated above 9/10 are the 'masterpieces'.
I find technical aspects to be of little to no importance to rating a game. Even the amount of content isn't necessarily what gives anything a high score. It's rather about the level of fun and satisfaction a game gave and how likely it is that I'll replay it, how valuable it is for me and how well it suits with my preferences. Even Zelda games, which is by far my favorite franchise, only managed three 9+ games.
I'll name them:
10/10
The Legend of Zelda: Ocarina of Time N64
9.5/10
Star Wars: Knights of the Old Republic PC
Super Mario 64 N64
Super Mario World 2: Yoshi's Island SNES
The Legend of Zelda: Link's Awakening GB
9/10
Sim City 4 PC
GoldenEye 007 N64
Mario Kart 64 N64
Super Mario Bros. 3 NES
RollerCoaster Tycoon 2 PC
SoulCalibur DC
Anno 1602 (US: 1602 AD.) PC
Super Mario Galaxy Wii
The Legend of Zelda: Twilight Princess Wii
Kula World (US: Roll Away) PS
Rome: Total War PC
Uncharted 2: Among Thieves PS3