Greedy Raven writes, "World of Goo can best be described as a tower-building physics simulator. Each level starts you out with a collection of round balls of goo. These balls of goo are strung out and used to build a tower towards a pipe somewhere else on the level. The player's goal is to attempt to build a tower using the fewest number off goo balls as necessary, in order to get as many as possible into the pipe. When the tower gets close enough, the pipe turns on a sort of vacuum suction and the roaming goo balls are whisked away..."