There are a number of ways you can complete a level in World of Goo, by far the commonest is the pipe, but if you want something a little different there are several other options.
In the original game these other types of "exit" were used almost exclusively on the final level of a chapter. If you use any of these exits you should be aware that on "completion" the player will not be returned to the Chapter 1 Island screen, but to the main World screen. Also these other exits do not display the normal end-of-level sequence (Continue Handle -> Tank -> Level Stats), they jump immediately to any cutscene* then to the World screen.
This type of exit was used in "Reguritation Pumping Station", it has a single attribute y which specifies a height.
The level will end if any attached Goo Ball is above this height.
NB: If an attached Goo Ball begins the level above this height, the level will end immediately.
This type of exit was used in "Product Launcher" and "Observatory Observation Station".
The level will end when two particular geometry objects collide (touch).
id1 and id2 are the ids of the geometry objects which must collide. There is one other attribute delay, this specifies the number of seconds after the objects collide, until the level actually ends. During this time the level remains completely playable.
This end condition was not used in any of the original levels, but is in the game code and does work.
Simply, the level ends when there are no dynamic geometry objects remaining.
Dynamic objects can be destroyed in 2 ways...
You may add more than one end condition to your level. In this case if any one of the possible conditions are achieved.. the level will end.
This end condition is used in "Deliverance" and "MOM", and ends the level after a particular message is displayed. If an UndeletePill hits a Ballbuster or a [Mostly]Deadly, it shows the popup, and ends the level if you have endonmessage set to END_DELIVERANCE. Otherwise, it will crash.
*Note: cutscenes are unavailable in the current version of GooTool.