NES.app lets you play Nintendo games on your iPhone. It is a fully functional, feature-rich Nintendo emulator. NES.app uses an emulator core called NESCore, which was forked from pNESx and InfoNES and re-engineered as a highly-portable and high-performance Nintendo emulator core.

In order to use NES.app, you will need ROM images of Nintendo games. ROM images are files containing the dumped instruction code from a physical cartridge. In many cases, you are legally entitled to posess a ROM image of any game that you presently own. ROM images for NES are widely available online, or with the appropriate hardware, you can dump them yourself directly from the cartridge.

Features
Multitouch: Use the directional pad + A + B, or other combinations
Landscape Mode: Turn the iPhone counter-clockwise to play in landscape mode
Zapper Tap: Tap objects on the screen to shoot them
Full Screen: Enlarge your NES picture to the max possible
Save State: Save an instant snapshot of your game and come back to it later
Game Genie: Use Game Genie cheat codes… and many more

NES.app is not iPhoneNES!
NES.app started as a fork of iPhoneNES v0.01, but has been completely rewritten to run very fast, and with many additional features including sound, multitouch support, full-screen, landscape mode, game genie codes, saved games and much more. It now contains zero code from the original iPhoneNES project.

As of recent, stepwhite re-released a much older version of NES.app as iPhoneNES v0.31. I have no idea why, but please be aware that NES.app is in no way affiliated with the iPhoneNES project (which only ever released v0.01 officially). I recommend using the latest version of NES.app instead, which is available below.

ROMs go in /var/root/Media/ROMs/NES (for those of you who don’t read the README).
Source Code

The source code can be downloaded via svn:

svn checkout http://svn.natetrue.com/nesapp

NES ROMs
NES ROMs are widely available on the Internet, and can be easily found using a serach engine. I do not condone the piracy of Nintendo games, however fair use may legally entitle you to download (or dump) the ROMs for games which you presently own, depending on your country of origin.

Download NES.app here
and here
Download the NES emulator + games from here
Please always read documentation before hacking your iphone, it can be damaged and remember Apple doesn’t honored warranty for hacked devices. Got it?

The NES Emulator in Action

Complete information about the NES Emulator
FEATURES

MULTITOUCH

NES.app uses the iPhone’s multitouch sensor to deliver a controller
environment very similar to the original NES controllers. This allows
you to “Run with B”, and so forth. The multitouch programming also allows
you to drag your finger to a different direction or button.

Note: “rolling” your thumb between A & B will allow you to depress both
buttons, just like on the original controller.

ZAPPER

The iPhone’s touchscreen makes for a great way to implement the zapper
gun. Just tap the screen where you want to shoot. Zap-Tap works on many
games including Duck Hunt, Hogan’s Alley, and others, but does not work
at all on the more nonstandard games, such as Chiller and Freedom Force.

SENSORY PAD

Since there is no tactile feedback on an iPhone, it may be more desirable
to play some games with a controller that measures motion, rather than
presses on specific buttons. Activating the ‘Sensory Pad’ option causes
NES.app’s directional pad to track with the motion of your finger,
regardless of where inside the sensory pad you are touching. When sensory
pad is active, the directional pad is replaced with a yellow track sensor.

SOUND

Sound is played through the iPhone’s native interface, allowing you to
hear email dings or accept phone calls while playing NES.app.

FRAME SKIP

Using the frame skip option, games that otherwise might run slightly slow
on your iPhone can be made playable.

An auto-frameskip option is the default, which continually adjusts the
frame skip and frame wait to make your games play as smooth as possible.

FULL SCREEN MODE

Using the full screen option, you can zoom in on your favorite game as
close to “full screen” as the NES aspect ratio will allow.

NOTE: Using full screen mode slows down the display a bit, so your
frameskip will typically bump up by 1, making the game more choppy.

LANDSCAPE MODE

NES.app takes advantage of the iPhone’s tilt sensor and will
automatically switch to a landscape-based view when you tilt your phone
to either side.

SAVE RAM

Games with battery-backed RAM, like Zelda, are automatically saved
to preserve your character data.

SAVE STATE

NES.app can save the state of any game when you exit. Unlike save ram,
which only for certain games with battery RAM, this option allows you to
take a “snapshot” of your game in progress, and come back to it later
right where you left off.

You can choose to start a fresh game from the “All Games” menu, or tap
“Saved Games” and load your previously saved game.

The game state is stored separate from save ram, so if you are playing
games like Zelda, where your game is usually stored to battery ram,
you will not need to save state unless you want to save an exact
snapshot. The save ram from the game is automatically stored
regardless of whether you save state.

TWO PLAYER CONTROLLERS

Although NES.app does not support netplay, you can toggle between
first and second player controllers by tapping the gray bar at the top
of the controller. The controller will change from red to blue to
identify itself as the 2nd player controller. Tap again to switch back.
This is useful for some 2-player games where the players take turns,
and for ROMs like the 1990 World Championship ROM, which requires the
second controller to start.

GAME GENIE

Game Genie was a popular cheat system for the NES. Many cheat codes are
published on the Internet. Up to four game genie codes can be specified
per game via the preferences menu. Load a ROM, then back out into
preferences to edit the genie codes.

NOTES:
Game genie slows down the game slightly, as the CPU is constantly
having to match read addresses with genie codes. This may increase
your auto-frameskip or require a bump if manually adjusting it.
Leave the genie switch “off” when not using it.

It’s also a good idea to turn off full-screem mode if you’re
using game genie.

TIP: For complex codes to start on a particular level, you can
enable the code, then save your game after beginning, disable
the code, and run at full speed again.

PREFERENCES

The following preferences are available by tapping the ‘Preferences’
navigation button…

Auto-Save Game
When active, every game you play will be automatically saved when you
leave the game. You may re-enter the game where you left off by
tapping ‘Saved Games’ from the top of the menu. If you decide to
start a new game, your old saved game will be overwritten.

Swap A/B
Swaps the A/B buttons around. NOTE: The labels do not change, only the
function.

Allow Suspend
When active, this allows you to push the home button, or accept a
phone call from within a game. When you return to NES.app, the game will
continue where you left off. When this feature is disabled, NES.app will
promptly quit instead.

Full Screen
Stretches the game screen to as large as possible, while maintaining
aspect ratio. NOTE: This impacts performance slightly.

Sensory Pad
Changes the directional pad to a sensory pad, which sets the direction
based on finger movement.

Game Genie
Activates any Game Genie codes you have entered at the bottom of the
preferences screen, for whatever game you happen to be playing.

NOTE: Leave this option off unless you are using it.

Advanced Options:

Frame Skip
Allows for manual adjustment of the frame skip. It is recommended you
leave this on ‘A’ for ‘Auto’.

Color Palette
This option allows you to change the color scheme of NES games to your
liking. The following palettes are available:

A: Standard palette, optimized for iPhone
B: Standard palette, unoptimized (used in older versons of NES.app)
C: Original NTSC palette
D: Original PAL palette

CPU Clock
The CPU clock controls the frequency of the CPU during rendering. As of
present best-practice, 339 provides accurate rendering for most games
and is the default. 341 can be used to tweak any games that you might
have a problem with, or if you find a game that doesn’t run using 339
cycles.

Bass Boost
Boosts the triangle wave output (responsible for most basslines).

Debug Mode
Debug mode draws colored rectangles over the hot spots of your game
controller, and also writes a diagnostic log to /tmp/NES.debug for
development.

NOTE: Leave this option off unless you are using it.

Add -DDEBUG to your CFLAGS to build with this option

HOW DO I…

Q. Upload ROMs to my iPhone?
A. Try iPhuc, iFuntastic, iBrickr, or set up SSH on your iPhone

Q. Reset my game?
A. Tap ‘ROM List’ and then tap your ROM again

Q. Adjust my volume?
A. With the volume buttons on the left.

Q. Use the player 2 controller?
A. Touch the top gray bar to switch between player 1 and player 2. The
controller buttons and text will change from red to blue when 2 player
is active.

Q. Press A & B at the same time?
A. In recent versions, you can now roll your thumb from one button to the
middle of both buttons. Both A and B should show up in the active control
window. Sliding your thumb from one side to the other will gracefully
switch between the two buttons.

COMPILING FROM SOURCE

0. You will need to install arm-apple-darwin toolchain v0.30 or above.

http://iphone.fiveforty.net/wiki/index.php/Toolchain_Project

Set your HEAVENLY environment variable to point to your iPhone environment.

You will also require AudioQueue.h from Leopart’s AudioToolbox framework.
I cannot provide this. If you own Leopard, locate this file and copy it
into your toolchain includes in AudioToolbox/AudioQueue.h if necessary.

1. Compile using ‘make’

This will create a new NES.app package in ./build.

Upload entire NES.app directory into /Applications on the iPhone and either
reboot the iPhone or run “killall SpringBoard”.

The iPhone should automatically detect the application and add it to the
springboard.

2. Place your ROM files in /var/root/Media/ROMs/NES
You will need to use a tool such as iPhoneInterface, iFuntastic, or SSH

KNOWN ISSUES

SOUND

Occasionally, the sound may appear to play severely lagged; at about half
speed. Rebooting the phone appears to resolve this. This appears to be
related to the sample rate of whatever sound was last played on the iPhone
(prior to launching NES.app) and has only been exhibited in 1.0.x firmware.

PAL VS. NTSC

NES.app supports both PAL and NTSC games, however not all PAL games are
appropriately identified as such in their headers. You can force NES.app to
identify a game as a PAL game by adding the text (E) to the filename
(including the parenthesis). For example: Tetris (E).nes. It is recommended
that you title all of your PAL games in this way, to ensure they are
clocked properly.

NESCORE

NESCore is an emulator core we originally forked from InfoNES, which was left
as a defunct and buggy NES emulator. We’ve since heavily modified and
rewritten many pieces of it, and given it a new birth as a portable LGPL
emulator core.

The NESCore project can be found at http://www.zdziarski.com/projects/nescore/