Ask HN: Where to find good CTF / wargame platforms?

These days I am very interested in learning about computer security / cryptography by practice and I find that CTF / wargames are very practical ways of learning about these subjects. After a quick google search I did not find that much on HN: site:news.ycombinator.com ctf wargame intitle:"Ask HN" I am seeking more platforms to train my skills and learn new things. Here are some I already know of and am working on: - http://overthewire.org/wargames/vortex/vortex0.html - http://www.root-me.org/ - Stripe CTF - Matasano Crypto Challenge Please post the ones you know about with a symbolic representation of difficulty (* = easy, * * * * * = extremely hard).