- The Sims 1 for PC sold 16 million copies (source).
- Halo 3 for the Xbox 360 sold 8.1 million copies (source).
- Half-Life 2 for PC sold 12 million copies (source).
- Super Mario Land 3D for the Nintendo 3DS sold 8 million copies (source).
- Super Mario Galaxy for the Nintendo Wii sold 10.68 million copies (source).
- Half-Life 1 for PC sold 9 million copies, not including Steam re-release (source).
- Pac-Man for the Atari 2600 sold 7 million copies (source).
Well, there's plenty more statistics about video game sales at this Wikipedia page, so jump on there if you want to compare it to other top-selling games. Check out the source link for Notch's tweet.
Source: Twitter