Modder Chris Hackmann (LeggoMyFroggo) has built the Time Frog Color, a 38 mm wristwatch that runs Game Boy Color games on original GBC hardware and accepts tiny physical cartridges, with an RP2040 handling display signal translation while preserving basic timekeeping when powered off. The build is an impressive, if impractical proof of concept, hampered by a very small screen, clunky controls, limited battery life, and no audio.