Jun 23, 2011 08:52 GMT  ·  By

Gabe Newell, the current managing director at Valve, has said that Portal 2 has managed to sell more than 3 million copies since launch and is on track to get better overall sales figures that the first title in the series.

Newell was talking at the Games for Change conference at the Games for Learning Institute and has not specified whether he was only talking about boxed copies or whether the 3 million number also integrated the games that were moved to gamers through Steam.

The number was used by Newell to show how a game can be successful in the traditional video game market while also offering the tools needed for teachers to show their students how various physics laws work.

Portal 2 managed to take second spot in the United States NPD Group delivered video game chart for the month of April and took a fourth place for May, which is pretty good performance considering the competition the Valve game was up against.

The game was critically acclaimed on launch and received close to perfect reviews from the major outlets, including a very positive one from Softpedia.

The big innovation for Portal 2 was the addition of a cooperative game mode built upon two robots with wildly different personalities.

The core game has also been altered with gels and with testing rooms that have moving panels.

Valve has not said whether it plans to extend the shelf life of Portal 2 by launching extra downloadable content for the video game.

At the moment the company is only confirmed as working on Defense of the Ancients 2, a game that is based upon the popular Warcraft III mod and could be free to play when it arrives, probably next year.

Valve has not said how many Portal games it plans to deliver, but the success of the second one probably means a sequel is being planned.