I have been recently pointed to the Python Challenge when I mentioned I was wanting to learn Python. Watch out for your eyes, nasty UI ahead...

What a great site! The game is fun, challenging, and educational! You "simply" have to solve the riddle posed on each screen (preferrably using Python, but any language/tool will suffice) and then put the answer into the URL to move on to the next question.

So far, the questions haven't been that difficult except for the time it takes to read through the Python Tutorial to get the skills/method names necessary to answer the next question.