Recently, an NES emulator called Bimmy appeared in the Apple App Store. But it disappeared within hours because, according to developer Tom Salvo, he was afraid of retaliation from Nintendo, AppleInsider reports.

Bimmy was created without any action from Nintendo or Apple. According to a post on the MacRumors forum, he removed it out of fear of retaliation.

“Pulled by me, just out of fear. No one pressured me to, but I got more nervous about it as the day went on. Very sorry to get everyone’s hopes up, but hopefully hopefully there will be other more brave devs than me in the future,” the developer wrote.

Software emulation has been around for decades and is perfectly legal, at least technologically. The implementation of emulators, business models, and ways for users to get games are in a gray legal area that developers are afraid to learn from their own mistakes.

Apple’s emulator guidelines don’t say much about legality. But they seem to put the blame on the developer if any legal action is taken. Again, emulators are legal if implemented correctly.