NES Emulator for iPhone & iPad | Retropa

File formats Retropa accepts for NES

Retropa does not stop at one extension for NES. The cores also take Famicom Disk System images and NSF sound files, and they handle both the plain and unified iNES container variants alongside the usual .nes cartridge image.

• A .nes file is the standard NES cartridge image.
• Famicom Disk System content uses .fds.
• The .nsf and .nsfe formats hold sound data, not a playable game.
• You can import ZIP and RetroPack containers and open them where they sit.

Which NES core to run

Three cores can start a NES title here: RusticoNES, TetaNES and JGenesis. RusticoNES is the default path, and testing a second core is the fastest way to tell a fussy ROM from a real emulation difference. Your pick is remembered per game.

• RusticoNES is the default and a steady pick for cartridge games.
• Reach for TetaNES when a game misbehaves.
• NSF audio behaves differently from a game, whichever core you use.

Import a NES game

Get the file onto the device first; a cloud-only entry in Files will not import. Open the library's import entry, pick the game, and launch it with the default layout. Check picture, audio and the stock buttons before you touch skins or filters.

Handling a two-button controller

There is not much to an NES pad: a directional pad, A, B, Start and Select. On glass, the urge is to bunch the buttons together, so test that diagonals still register and that you are not catching Start or Select mid-game. A paired physical controller sidesteps most of it.

• Pair the controller in iOS, then check how Retropa maps it.
• Test diagonals, not only the four cardinal directions.
• If you switch orientations, test both.

Getting the picture right

These titles were authored for a standard-definition television, which is why a CRT treatment often reads truer than a clean pixel grid. Scanline and aperture-grille presets are on hand, and Retropa's advanced filters follow the real output area instead of a fixed integer multiple.

• Keep the original picture around as your reference.
• Plain scanline overlays can shimmer when the scale is not a whole number.
• The advanced filters are a Retropa Plus feature.

When a NES game will not load

Read the error text before touching any setting. A bad dump, an unsupported mapper, a headerless image and a disk game with no BIOS are four separate problems. Confirm the extension and the selected system, then run the game on another NES core.

• Note the app version, the core and the full error text for support.
• Leave the original file alone while you work out what went wrong.
• Do not attach commercial ROM or BIOS files to a support ticket.