Tower of Goo Unlimited is the original prototype, made some years ago, of World of Goo, a famous indie game for Pc and Wiiware. Even if you can create only a tower in this concept, the basic gameplay and the graphic style are essentially the same as the released version. There is a level called “Tower of Goo” in the final game, but it is much more technically refined.
2dboy has a prototype section about the development of World of Goo.
Images:
Video: