The game is built around the idea of creating large structures using balls of goo. The game is divided into five chapters, each containing several levels. Each level has its own graphic and musical theme, giving it unique atmosphere, similar in style to Tim Burton's film designs. There is also a bonus meta-game called World of Goo Corporation, where the objective is to build the highest tower using goo balls which the player collected through the course of the game. Players from all over the world can compete, as the height of the tower and number of goo balls used are being constantly uploaded to the 2D Boy server.
Objective
The main objective of the game is to get a requisite number of goo balls to a pipe representing the exit. In order to do so, the player must use the goo balls to construct bridges, towers, and other structures to overcome gravity and various terrain difficulties such as chasms, hills, spikes, or cliffs. There are several types of goo balls in the game, each of which has unique properties. The player must exploit combinations of these goo balls in order to complete each level. Extra goos recovered in the pipe are pumped through to the World of Goo Corporation, a sandbox area where the objective is to compete with other players worldwide by building the tallest tower possible. Players can also try to achieve the "Obsessive Completion Distinction Flag" for each level by completing the level under more stringent criteria, such as collecting a larger number of Goo balls, finishing under a set amount of time or using as few moves as possible.
Levels and chapters in the game are interspersed with cut scenes.
The WiiWare version includes multiplayer with up to four people on the same Wii. This facility is also available, albeit unsupported, in the Linux port.
Levels
World of Goo is split up into five chapters, each containing a number of levels. The chapters are set over the course of one year in the World of Goo. Each chapter takes place over one season, beginning in the start of summer, and ending at the end of spring the next year.The 4th chapter is seasonless, and is set in a virtual world.
An additional 'chapter' selectable from the main menu is the World Of Goo Corporation. Goos collected above and beyond the required amount to pass a level are piped out of each of the played levels to here. Starting from just a single triangle of Goo, the aim is to build the highest possible tower. The Goos in the World of Goo Corporation are unique in that they can be repositioned like Ivy Goos but are black and can only form two connections at once like Common Goos.
In the World of Goo Corporation, towers built by other players of the game are represented by clouds bearing the player's name, nationality and height of the tower, including details on the total number of balls collected by the player and how many were used in constructing their tower. The altitude of each cloud represents the height of that player's tower. An online leaderboard charts the heights of the top 50 towers, as well as the top 10 players for each level of the game.
There are a total of 48 levels in the game, including World of Goo Corporation.
In an interview the developers stated that the retail version released in Europe would receive an additional sixth chapter, set on the Moon. Few details were disclosed, but reportedly this chapter would have featured a freeform sandbox mode, similar to that of the World of Goo Corporation. This addition was, however, canceled for Wii when 2D Boy announced they were releasing the game on WiiWare in Europe.