[Lyrkan]

I'm wondering if selling physical copies of the game doesn't come with legal issues...

The "Nintendo" logo you see when booting a Game Boy comes from the cartridge and is checked against one stored in the console.

If they don't match the whole thing stops, which means that you have to add (and distribute) a Nintendo logo to your game in order for it to work on real hardware.

[philistine]

I have not tested this particular game on real hardware, but multiple games found ways around the console's logo checksum. It has a buggy implementation that can be circumvented, allowing you to never have the logo on your cartridge.