Valve is bucking one of the largest trends in the video gaming industry — releasing additional content for games and charging extra for it — by releasing the next phase of content for its blockbuster hit Portal 2 for free for all gamers.

Downloadable content for games can be as big as the blockbuster games themselves. The Call of Duty series, a first-person shooting game set in wartime, has proven this point multiple times by selling additional maps for its multiplayer games. But the additional costs can frustrate some gamers that might think they are being charged too much for content that should already be in the game. Valve — which regularly delays its games so they are at their best when they are released — could be using the opportunity to build up additional good will with its users.

Not that it really needs to do so. Bellevue, Wash.-based Valve recently launched an alternate reality game related to Portal 2. Alternate reality games are difficult to pull off, because they involve fans guessing about the game and trying to solve puzzles that span the entire Internet. But if a company can pull it off, it can generate an enormous amount of excitement for the game. Valve was successful by giving players the power to release Portal 2 early if they solved the puzzle, and had players frantically working until hours before the game’s official release time to do so.

Portal 2 is the sequel to the hit game Portal, which has players controlling a test subject with a gun that creates doorways between two parts of a level with a portal gun. The game also featured a cynical and hilariously dark antagonist, artificial-intelligence GLaDOS. The game was a massive commercial success when it was released with the Orange Box, where it was packaged with Half Life 2 and Team Fortress 2 — two other critically acclaimed games.

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Portal was a fairy-tale success story for independent game developers. The game was a successor to an independent game called  Narbacular Drop, which was developed by a group of students from the Digipen Institute of Technology. The students were hired by Valve and spent a little more than two years developing Portal. Its successor has so far held up well with Critics too, picking up a score of 95 out of 100 across 37 reviews on review aggregation site Metacritic.