Valve’s puzzle solving platformer sequel, Portal 2, was released in North America yesterday and hits European retail shelves tomorrow, while South African’s will have to wait until Friday. Unless you buy it through Steam, which you can do right now.

To celebrate the occasion, Valve has announced that the original Portal sold just under 4 million copies around the world, and that’s excluding Steam sales. Portal was released as part of Valve’s Orange Box in 2007, where it accompanied Half Life 2: Episode 2 and Team Fortress 2.

In 2008 Portal was released as a standalone game.

Portal 2 has already received an excellent reception, with most games publications awarding it a score of 9/10 or higher.

Still on the fence about Portal 2? Check out our Portal 2 review roundup