The wargames offered by the OverTheWire community can help you to learn and practice security concepts in the form of funfilled games. To find out more about a certain wargame, just visit its page linked above. If you have a problem, a question or a suggestion, you can join irc.overthewire.org on port 6697 using an SSL-enabled IRC client, or irc.overthewire.org on port 6667 using a regular IRC client.
This is like a text adventure, except its unix/cryptography/C.
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.