Tomu is a super cheap Open Source Hardware 24 MHz ARM computer with 8 KB of RAM and 64 KB of ROM that fits into your USB connector! Michael Steil had to put Commodore 64 BASIC on it, which can be accessed through the USB-Serial port exposed by the device.
Use a terminal emulator to connect to the virtual serial port and hack away!
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.