If you're looking for a way to play old NES games on your iPhone, there is no longer a need to jailbreak. This works on any firmware and idevice. This is iPhone 5 widescreen supported and ipad 3 retina supported. This emulator has a built in option to download roms which is fast and easy. Follow the simple steps below. Remember, there is no risk in this.
Step 1: Open Safari on your iDevice
Step 2: Type in this url in Safari: emu4ios.weebly.com/downloads
Step 3: Scroll down until you find "Nescaline" and hit "Install"
Step 4: Now allow it to download to your homescreen
That's it, follow the steps in the emulator to download roms. You can always delete this app when you want to get rid of it.