Masterplay alike adapter with support for Sega Genesis (3 or 6 button) and Nintendo (NES or SNES) controllers and provides START and PAUSE keys functionality for convenience. Remaining functions can be accessed by a standard joystick connected on the 16 vias IDC connector on the board.  

Buttons and keys are mapped as follows:

Two printed circuit boards available. Compact board measures 1.6"x1.6" (41x41mm)

A second version of the board fits inside a Hammond 1593J case:

Work in progress.

Project repository available at Github