The board is designed in KiCad and uses a dual sided pcb while only using one side for the components. It features an ATtiny84 with 6 LEDs and a switch powered by a 3 V button cell. The example above was manufactured by OSH Park.
The challenge is to come up with your own interesting light shows, games, etc. for the badge. This repo includes a basic Arduino sketch using the ATTinyCore to get you started.
Use some crocodile clips and an AVR ISP programmer like a standard Arduino UNO with the ISP sketch and a 10 μF capacitor.
The design and example firmware are licenced under GPL-3.0-or-later.