And when you connect all the top circles with all the bottom circles it looks like this:
But the aim of the game is that the nine lines don't cross. That basically is the Utilities Problem also sometimes called the Water,gas and electricity problem. If have never tried this before stop reading, start drawing and have fun. If you have tried it before, please continue.
The next level...
While browsing through some YouTube video's I was looking at a video on the Numberphile channel. This has some entertaining video's on mathematical subjects which are still fun even if your not that into math normally. Long story short, they had a link to a website that sells math gadgets and it's called Mathsgear.
One of the products they sell is a mug with the Utilities Problem drawn on it. So check that out, because it's a really nice twist to the problem.
You've hopefully thought about that mug. Maybe even tried it on a real mug. All you need is mug and a whiteboard marker, so nothing is stopping you.
I myself drew houses and utility symbols on my mug, tried lots and lots of lines and felt smarter in the end. I guess it was two days after the puzzling and annoying colleagues that a thought occurred to me. What if the puzzle was on a t-shirt? It would already be cool just have a puzzle on your shirt, but now the shirt is part of the puzzle. I don't want to spoil to much and just show the result. I added an extra utility but that is vital in any modern household, internet. This make the puzzle a bit harder. And no, it isn't wireless so don't try cehating. My drawing of the puzzle looks likes this:
I put the t-shirts in my own t-shirt shop Core Business. Could make a nice holiday present (hint hint).