I just came across Ed Skoudis' slides on the making of capture the flag games. It's quite interesting to flick through the slides and hopefully will inspire more people to create these types of games!

http://pen-testing.sans.org/blog/2011/12/10/sans-keynote-preso-put-your-game-face-on


slides: http://blogs.sans.org/pen-testing/files/2011/12/Put-Your-Game-Face-On-1.0.pdf

At the end of the slides there are links to a few different challenges, some have been featured on here! But you might have missed some.

I'll throw a quick link out for https://pwn0.com/ too. Just connect in with a machine and start trying to gain access to some of the pwn0bots. It's good fun, but don't forget to nail down the system you connect in with

Cool sounds like fun may have play if I get any free time, Thanks for the links.