For some time now I looked for a time off activity and last Saturday I settled on doing some wargames. I quick search came up with overthwire.org.
They have a decent beginners game called bandit.
It took me, with no wargame experience but some decent Linux/bash skills about an hour to burn through 25 of the 26 levels.
The last level was quite a challenge. I had the right approach mapped out, but tried to achieve it with the wrong mechanisms. I finished this level the next day. In all it took me 2 hours of reading man pages.
I can only recommend this to everyone. This is also a great way to learn some Linux and bash things on the way.
I refrain from posting solutions, that would take the fun out of it. So go and try it out yourself.
Just log into *bandit.labs.overthewire.org with username bandit0 and password bandit0. Hints start at Bandit 0. you mostly need man pages if you are unsure about stuff.
If you know of a cool wargame hit me up on Twitter.