Just recently, I found this cool website CodeFights. I find it fun and I want to share it with you.
The idea of the site is to improve your debugging skills. The site provides you short codes, which have a bug in one of their lines and you have limited time (1-3 min) to find and correct it. It is still Beta and the codes are written in JS. The codes are short, simple and most programmers will find them easy to read and debug. I hope they add more languages soon. There are many achievements/badges. The detailed rules are simple and you will understand them in a game (or two).
I hope you like it.
I asked them if they are going to add more languages and they replied this:
— "As for adding more languages, happy to let you know that we are very close to releasing 3 new languages including C++ ;)." — CodeFights.