Sebastian Staacks' RP2040 Game Boy Interceptor Lets an Unmodified Game Boy Stream Gameplay Videos

Physicist and self-confessed "nerd" Sebastian Staacks has created a device, which allows an unmodified Nintendo Game Boy handheld console to stream game footage, using a Raspberry Pi RP2040 microcontroller: the Game Boy Interceptor.

"Allow me to tease the Game Boy Interceptor," Staacks has announced via Twitter, "an RP2040-based adapter that goes between your (unmodified) Game Boy and the game cartridge to record or stream your gameplay. The Game Boy [is] directly connected to the game without any interference from the adapter. The adapter only listens to the communications and reconstructs the image by following the instructions that the Game Boy receives from the cartridge and emulating its graphics."

The gadget means a big breakthrough for retro-gamers looking to capture high-score runs or live-stream gaming sessions: while full-size consoles can be connected to a capture card with ease, handhelds with their built-in screens are more difficult subjects. The solution is typically to use an emulator instead, or to point a camera at the screen — the former lacking the guarantee that what you see is as it would originally have been, and the latter lacking in quality.

The Game Boy Interceptor, by contrast, sits somewhere between real-metal playback and emulation "I would call it 'emulation on rails,'" Staacks explains. "The Game Boy's program counter actually drags my code through the instructions, so I do not have to implement any conditional jumps, but there is still a lot to emulate, including the entire PPU [Picture Processing Unit]."

While functional as-is, though, the device isn't quite there yet: "In the video you can see several glitches because of bugs or missing functions," Staacks admits. "For example, you cannot see falling stones because I have not yet implemented sprites and the line counter is weird because of a bug in my DAA instruction (at least I think so). The refresh rate with this hardware will be a bit below 30 frames per second (actually 24 in the video, skipping 2 and 3 frames)."

Staacks has promised to release the Game Boy Interceptor under an open-source hardware, both for the firmware and the hardware design files — but has pledged to work on the software, design a case, and possibly go through another hardware revision prior to release. "I hope to finish it this year," he writes, "so stay tuned."

Those interested in following Staacks' progress can find more on his Twitter feed.