Instructables user fasaxc only had about 24 hours to make a costume for a party and constructed a playable and wearable giant Gameboy. He made sure he could get a Gameboy emulator running on his laptop and then printed a photo of the front of a Gameboy onto several sheets of paper. It was a quick fix for this costume – he prefers to paint and sculpt. After the glued the papers onto a cardboard box it was time to mount the electronics. The Gameboy’s screen is simply a laptop that fasaxc folded out flat; he used gaffer tape to keep the laptop in place and rested the computer on a cardboard ledge.

Here’s how he made the buttons work with Arduino:

At this point, I had the laptop mounted, Tetris loaded and it’d run through its demo loop every minute or two. But I wanted buttons! Sorry for the lack of pictures, I was down to about 2 hours to go at this point…

Time to put my Arduino to work. The path from button to gameboy looks like this:

Button is pushed, closing the circuit from ground to one of the digital input pins (I used the internal pull-ups so the pins normally read HIGH until the button is pushed).
Arduino reads inputs every few msec, detects button push.
Arduino debounces the button push.
Arduino sends signal over its built-in serial port emulator for each button push. (What you see in the Arduino serial monitor.)
Python app reads the serial port, maps the raw data to the correct key to be pushed.
Python app uses “xte” to emulate a keypress, feeding it to the current application. Note: this is Linux-specific, the code would need to be totally different for Windows.
Gameboy emulator sees the keypress and voila(ish)!
Can’t recommend Arduino enough for this sort of thing. I had an LED blinking in 1 min, then serial communication up in 5 mins. Luckily I had some Python code lying around for reading the serial port so the main problem I had to solve was getting the input into the emulator.

See the costume in action:

https://www.youtube.com/watch?v=H0TxI4N_Drw

Read more about the build at Instructables.