Chris Hackmann — better known online as LeggoMyFroggo — has been making increasingly unhinged Game Boy Color projects for a few years now. The Frog Boy Color put GBC hardware in a Game Boy Advance-style horizontal shell. The Tad Boy Color made it smaller. The Time Frog Color, his latest project, shrinks it to 38mm and straps it to your wrist. It took two years. It runs on actual Game Boy Color hardware. It plays physical cartridges. It has no audio. It is completely impractical and genuinely impressive.
The Rules
Hackmann set himself three conditions at the start of the project. The watch had to use the original Game Boy Color CPU. It had to play physical game cartridges — not ROMs loaded from an SD card. And when not being used as a games console, it had to keep time. Anything less, he decided, and it wouldn’t qualify as a real Game Boy watch.
Those constraints created most of the difficulty. An emulator on a modern microcontroller would have been trivial. Using actual 1998 GBC silicon in a 38mm case is something else entirely.
How It Works
At the core is the original Sharp SM83 processor — the same chip in every Game Boy Color — alongside the video and system RAM required to run games. The problem Hackmann ran into immediately is that the original GBC display output isn’t compatible with any modern watch-sized screen. His solution was a Raspberry Pi RP2040 microcontroller acting as a real-time signal translator between the GBC CPU and a 1.12-inch colour display. He describes the RP2040 as a “poor man’s FPGA” in this context, which is an apt description.
The cartridges presented their own challenge. Original Game Boy Color carts are larger than the entire watch. Hackmann designed miniature functional replacements using M.2 connectors — the same type used for NVMe SSDs in laptops — housing a legitimate ROM chip inside each one. The result is a tiny physical cartridge that slots into the side of the watch. He demonstrated it running Pokémon Gold.
The battery is embedded inside the silicone wristband via a flexible printed circuit, which is either inspired engineering or a fire hazard, possibly both. It powers the watch in sleep mode and the console when gaming, though battery life is shorter than a standard GBC, which was already measured in hours rather than days.
The case is CNC-machined aluminium finished in Nintendo purple. Controls are tiny tactile switches under 3D-printed button caps. There is no sound.
What It’s Like to Actually Use
Hackmann is admirably honest about this. In his own summary: “It’s a Game Boy Color with a less-than-optimal playing experience, shorter battery life than most, and a right to exist just ahead of macaroni and cheese with ketchup.”
The screen is 1.12 inches. The controls are cramped. There’s no audio. It is not the best way to play Game Boy Color games — that’s what the Analogue Pocket is for. But that’s entirely beside the point, which is that a genuine Game Boy Color, running from real hardware, playing real cartridges, now exists in a form factor that fits on your wrist. That Hackmann spent two years making this happen because he set himself an arbitrary rule about what counts as a “real” Game Boy watch tells you everything you need to know about the modding community at its best.
The project will be made available on Hackmann’s GitHub once documentation is complete, for anyone who wants to attempt their own.
For more on the current state of retro hardware, see Is This the Golden Age of Retro Gaming Hardware?