I'd designed and built a circuit for a handheld gaming unit some time ago. In this project I've converted it into a portable gamebox of steampunk style. As the circuit has a real time clock and can display room temperature as well, the unit can be used as a practical table or wall clock in addition to be a display piece.
The circuit inside features a 8 bit microcontroller PIC 18F4620, several control buttons, two piezo speakers, an expansion port for extra memory or a position sensor. It also features a real time clock, so I planned the steampunk unit to be a decorative timepiece, demonstrating a game along with time. I wanted it to be also playable. It can be played in multiplayer or single player(against the microcontroller).
The games are the top of the line retro classics from the zx spectrum era. All of them are scratch written for the project; Snake 1-2 player, Tetris, Pacman. Even an etch a sketch drawing board program is also written.
I'll give circuit schematics and the hex codes of all games I've written for the gaming unit. But the project can also be done by using arduino, pi computer or any other gaming circuit you build.
I've used the circuit board as template for measuring the plywood parts. Used 3mm thick plywood I've found among scrap. It had an old lacquer layer on top that looks antic and nice.