As it's a series of articles going through the various World of Goo-versions they had before the final, there's no need to go throug TIGSource, just go directly to 2DBoy.com. More specifically http://2dboy.com/category/world-of-goo/page/2/ for the beginning of the series.

Look at the end of that url. The "/page/2/" means it's currently on the 2nd page of their blog.

As they post new items it will eventually slip out of page 2, and that url will not be as useful in a few weeks/months/years as the tigsource page.

Continue following the next links on that.

There are a lot of unrelated blog posts between some of the parts.

Is linking to tigsource really such a taboo?