not a puzzle

I have told most of the people I know already about this puzzle, but still wanted to blog about it.
Friend of mine got me hooked onto it and every weekend, I spend atleast couple of hours on this site.

Supposedly one of the toughest puzzles online and the inspiration for many other famous puzzles. Only 94 people have been certificated for finishing the game for the first few months of its creation. That's about 0.001% of all. Notpron has 138 levels. 35 positive, after which there are 35 negative and once you solve all of them, you enter the greek levels. I am far from them right now.

Here is the starting page notpron and here is the forum which has hints to solve the levels, but no spoilers.