Emulators themselves are on fairly well-established legal ground, but the ROM files required to play all of your favorite classic video games are far sketchier. Technically, if you rip a copy of a game yourself as a backup, you’re in the clear… but since few have the technical acumen or equipment to do so, they usually resort to downloading the ROMs from warez sites.
That’s primarily the reason why Apple has traditionally kept its App Store so closed off to emulators. So expect Nescaline, an NES emulator for the iPhone and iPod Touch, to be pulled as soon as Apple gets wind of it.
On sale for $6.99, Nescaline has a full feature list, including multitouch, light gun and save state support. It ships with five homebrew NES games, which is certainly legal. Unfortunately, its cardinal sin — at least in the eyes of Apple — is allowing users to input a URL where they can download additional ROMs. That means it’s as easy to put a warezed copy of Castlevania III on your iPhone as it is to cut-and-paste a Google search.
Expect Nescaline to be pulled quick, and if it comes back to the App Store at all, for the download feature to be neutered. Unfortunately, for right now, if you want to play emulators on your iPhone, legally owned games or not, jailbreaking is still your best bet.
Update: That didn’t take long. It’s been removed from the App Store.