Stacking is an adventure/puzzle video game developed by Double Fine Productions and published by THQ; like Double Fine's previous Costume Quest, it is a smaller title created during the development period of Brütal Legend, and was released in February 2011 for the Xbox Live Arcade and PlayStation Network stores. A Microsoft Windows version has been announced. The game is based on the Russian stacking matryoshka dolls, an idea coined by Double Fine's art director, Lee Petty, who saw the dolls as a means to replace the standard player interface used in graphical adventure games. The player controls the smallest doll, Charlie Blackmore, who has the ability to stack and unstack into larger dolls and use their abilities to solve puzzles to allow Charlie to free his older siblings and put an end to child labor enforced by the antagonist, the Baron. Puzzles within the game have multiple solutions, and include additional puzzles and challenges that allow the player to explore the game's world outside of the main story.