I really enjoy solving coding puzzles, such as the ones on this website. I feel like you can learn a lot from doing it, and it’s a great way to fill your coffee breaks.
Anyway, the BEST and most interesting codding puzzle I’ve ever seen is this: http://cryptopals.com/ (the matasano crypto challenges).
It’s essentially a series of tasks related to cryptography which get progressively harder. You don’t need to have any previous knowledge about crypto to do these tasks, and they’re not math-heavy. According to the website, “When you’re finished, you’ll not only have learned a good deal about how cryptosystems are built, but you’ll also understand how they’re attacked.”
I feel like the matasano challenges and the CodinGame platform would work amazingly together, in my opinion, the combination would increase the value of both sides.
This is just a thought I had and I hope it’s okay to share it!