The .gb file can be run on PC through an emulator, and there's also the SameBoy pack - SameBoy being a Game Boy emulator itself. I've included a .bat file in that package which launches the emulator with the game already loaded - you may need to adjust some of the emulator settings when running for the first time (I think SameBoy defaults to DMG - that's the original monochrome Game Boy model - so you'd need to choose Game Boy Color instead).