TM1638 Display / led / buttons board - This board is not Retro but can be used in retro emulations. With 16 buttons and 8 seven segment displays, it is a nice I/O board that can be connected to the Arduino with only three connections. A nice ready-made solution if you want to do Retro emulation on an Arduino type board. Datasheet TM1638: https://futuranet.it/futurashop/image/catalog/data/Download/TM1638V1.3EN.pdf Arduino LIB: https://www.arduino.cc/reference/en/libraries/tm1638plus/