It's something like protothypes from Experimental Gameplay Project.
But the author is not Kyle Gabler, but... Goosweek's Goomods Factory.

This is free area filled by Goo Balls working like this from Information Superhighway.
Two MODS allowed:
NORMAL - with vertical gravity
RADIAL - with central gravity like in Graphics Processing Unit.

Full information about options under F1 key.

Now introducing...
The World of Goo Corporation approved* mouse cursors for Windows!
Simply unzip the folder, put it somewhere safe on your hard drive, and go into Control Panel.
From there, find the mouse properties (should be somewhere close by, it's in "Appearance and Personalization->Personalization" in Vista), click on the "Pointers" tab, and start changing your mouse cursors to the appropriate ones from the package (use their names as a guide). When you are done, click "Apply" and Poof! Your mouse cursors are instantly World of Goo Corporation approved!

BIGGEST PLATFORMS OF GOO ADDIN EVER

The Ultimate Level Challenge (or ULC) is the biggest PoG addin level set in the game. The game itself has 2 games in the series based off Goosweek's Platforms of Goo. You must get the latest version of Goosweek's Platforms of Goo to install the addin.

THE ULTIMATE LEVEL CHALLENGE FEATURES
- 500 levels to finish
- 50 worlds to travel
- Facing different types of monsters with different abilities
- Side Levels Types: Time Bomb, Falling Blocks, and Can Chase
- Dazzling Graphics
- Soundtrack from the original World of Goo

THE ULTIMATE LEVEL CHALLENGE 2 FEATURES
- Worlds with unique taste of gameplay
- Sweet new graphics
- Over +50 levels and more to come
- 10 Parts overall

Bummed about the 300 gooball limit in World of goo Corp.? Then download Tower Of Goo Unlimited, all credit to Kyle Gabler. Just extract the zip file.
If necessary I will make a exe setup version.