Chris Hackmann's Time Frog Color Crams a Real, Working Nintendo Game Boy Color Into a Watch

Maker and Nintendo Game Boy enthusiast Chris "LeggoMyFroggo" Hackmann has followed up his Frog Boy Color and compact Tad Boy Color consoles with the smallest Game Boy yet — so small you can wear it on your wrist, despite using a genuine processor rather than emulation: the Time Frog Color.

"Because I'm a TOAD-al nutjob, I still gave myself three constraints," Hackmann says of the project, which effectively shrinks Nintendo's Game Boy Color handheld to the size of a smartwatch. "It has to use the original GBC CPU. It needs to be able to play cartridges of some kind. And to fulfill the whole 'being a watch' thing, it has to be able to maintain the time while turned off. Anything less and I wouldn't consider it a true Game Boy watch."

Nintendo's incredibly successful Game Boy family began with the launch of the original model in 1989, but that's not the version Hackmann was looking to reimagine. Instead, the project is based on the Game Boy Color — the 1998 successor to the Game Boy Pocket that leaned on the march of technology to shrink the handheld console's dimensions while adding a faster processor mode, additional memory, and a color LCD panel in place of the original's monochrome display.

Hackmann has form in building upgraded versions of the Game Boy Color: three years ago he unveiled the Frog Boy Color, which offered all the Game Boy Color features minus infrared but in a Game Boy Advance-style horizontal case, followed by the amazingly compact Tad Boy Color. The new watch-format variant, dubbed the Time Frog Color, though, goes smaller still.

To do that, Hackmann turned to a more compact, 1.12" display that can't be directly interfaced with an original Game Boy Color processor — using the programmable input/output (PIO) blocks of a Raspberry Pi RP2040 microcontroller to translate the signals between the two. meaning that the new gadget's display coprocessor outperforms its central processor by a few orders of magnitude.

Elsewhere in the casing is an original Sharp SM83 processor plus the video and system RAM required to run the games, together accounting for the bulk of the footprint. "I could have gone with the single-chip CPU-E revision," Hackmann notes, "but I'm not a quitter. By some miracle, these two chips side-by-side sit pretty comfortably within 38mm," a size target chosen for matching larger models of Apple Watch.

Perhaps the biggest challenge were the games themselves. Emulators load their games from ROM images, but Hackmann specifically wanted to be able to use physical cartridges. As these dwarf the size of the watch itself, the solution was to build teeny-tiny functional scale versions — with the maker settling on an M.2 connector, more usually used for Non-Volatile Memory Express (NVMe), SATA, and accelerator add-ons in desktop and laptop computers. The thickness of the watch itself was kept at around 15mm, thanks to a clever hack for power: moving the battery out of the body and into a cast-silicone watchband with pin connectors.

"If this all sounds needlessly complicated," Hackmann jokes, "have you even thought about this? It's a Game Boy watch. C'mon, buddy. 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. But in the end, I'm still shocked that I have a real playable Game Boy Color, in at least a technical sense, on my wrist."

The project is detailed in full in the video embedded above and on Hackmann's YouTube channel; the maker has pledged to release design files for building your own Time Frog Color alongside those for the Frog Boy Color and Tad Boy Color in the near future.