Onto the Arduino platform. It has its own IDE based on Processing. It is more C/C++ oriented than e.g. Phidgets. Gemma check. Including library for neo-pixel check (In the menu). USBtinyISP programmer check. Got an error:

avrdude: error: usbtiny_receive:  (expected 4, got -5)

But it did upload the program and thus it works. Good enough, although it would be nice to know what causes the error.

Update: Apparently these can be ignored: https://learn.adafruit.com/adafruit-arduino-ide-setup/troubleshooting