Wargames

I recently started a fun activity called wargaming. Wargames are a set of computer science related challenges/puzzles. So far I have completed three of the wargames on overthewire.org: Bandit, Krypton, and Leviathan. I track my progress on wechall.net. wechall.net tracks scores across dozens of wargaming sites and has user rankings/leaderboards. The wargames I have seen touch many different areas of computer science: cryptography, network security, linux tools, C++ debugging, etc. Very educational.