World of Goo is a physics-based game program designed by Ron Carmel and Kyle Gabler and is released by 2D Boy. It was initially released in October 13, 2008. The game is built upon the idea of constructing structures made of balls of goo. The main goal of the game program is to get the required number of goo balls reach the piper that represents the exit. To do this, players must build towers, bridges and other types of construction using the goo balls to overcome different types of difficulties in the program (e.g. windmills, hills, chasms, or cliffs).
The game has different types of goo ball with each of them having their own set of properties. Players must strategize on what goo ball combination to use to complete a certain level. Extra goo balls that are recovered at the end of the level are transferred to the World of Goo Corporation. This is a sandbox area where other World of Goo players complete worldwide in building the tallest possible tower. Players can also try to attain the Obsessive Completion Distinction Flag for every level by completing the level under stricter criteria. World of Goo has a total of 5 chapters – 4 chapters with 1 epilogue. Each chapter consists of a certain number of levels, a total of 48 levels.