Boards of ESP-IDF programs described once as data: pins, buses and parts, each fact with where it comes from. The board is chosen once; the component sets its hardware up through the library of each part, and the program asks for what it needs by kind, never by the board's name. A build downloads only the libraries the chosen board needs.
A small engine of 2D and 2.5D games on top of DGX: an indexed frame sent by its changes and scaled, pictures from a pack in flash, actors living by animation scripts, tiles, masks, a world that lives on, dialogs, a sound mixer