They didn't elaborate in the article I read.

Well they did release it open source... maybe I could mod it?

Well, I finished Osmos. I worked out what my problem was - I was too impatient, so I played the force levels at maximum speed and never slowed it down. This meant I often over-compensated for making moves, and wasted too much mass on manoeuvring, or over-shot my destination by too much. This also helped a lot: http://www.hemispheregames.com/2010/02/03/osmos-rage-part-4-roadside-assistance/

I finished the final attractor one in about 5 attempts, and the 2nd epicycle one with another 7-8 attempts. The final one took me about 10 attempts, but I did get a lucky spawn with lots of 'large' motes nearby on the starting attractor, which made the start of it pretty fast-going when I had to re-do it.

That's why there are those little glowing bugs to undo a few moves ...

Yes, a 'few moves' was the problem. If you were working on a solution and had to use a couple of them, and then it turned out the whole thing was crap and you only had 3 bugs left but really needed 5 to get back to a reasonable point, you were screwed and had to start the whole thing over. If it was unlimited undoes there'd have been no problem.

The one I was stuck on for a while was 'boney's love story' or something, with the strange frog and the first level where you got the bone goo-balls. Once I realised that you could detach and move the bone goo-balls from where you previously had them, it became much easier. The other one was where you had the bomb suspended from the ceiling and had to blow up both walls to get to the pipe - I realised what the trick to it was after a while, but for some reason I just couldn't see it initially, I thought you had to make some sort of brace system, instead of just a single suspending rope of goo.

Overall World of Goo was actually pretty easy and not much of a challenge.