Zelda3

A reimplementation of Zelda 3.

Our discord server is: https://discord.gg/AJJbJAzNNJ

About

This is a reverse engineered clone of Zelda 3 - A Link to the Past.

It's around 70-80kLOC of C code, and reimplements all parts of the original game. The game is playable from start to end.

You need a copy of the ROM to extract game resources (levels, images). Then once that's done, the ROM is no longer needed.

It uses the PPU and DSP implementation from LakeSnes, but with lots of speed optimizations. Additionally, it can be configured to also run the original machine code side by side. Then the RAM state is compared after each frame, to verify that the C implementation is correct.

I got much assistance from spannerism's Zelda 3 JP disassembly and the other ones that documented loads of function names and variables.

Additional features

A bunch of features have been added that are not supported by the original game. Some of them are:

Support for pixel shaders.

Support for enhanced aspect ratios of 16:9 or 16:10.

Higher quality world map.

Support for MSU audio tracks.

Secondary item slot on button X (Hold X in inventory to select).

Switching current item with L/R keys.

Installing Python & libraries on Windows (required for asset extraction steps)

1. Download Python installer and install
2. Open the command prompt
3. Upgrade pip & install pillow and pyyaml by typing python -m pip install --upgrade pip pillow pyyaml and hit enter
4. Close the command prompt

Compiling on Windows with TCC (1mb Tiny C Compiler)

1. Download the project by clicking "Code > Download ZIP" on the github page
2. Extract the ZIP to your hard drive
3. Place the USA rom named zelda3.sfc in the "\tables" subfolder
4. Open the command prompt and navigate to that folder
5. Extract resources by typing python extract_resources.py and hit enter
6. Compile the extracted resources by typing python compile_resources.py and hit enter
7. Close the command prompt
8. Download TCC and extract to the "\third_party" subfolder
9. Download SDL2 and extract to the "\third_party" subfolder
10. Double-click run_with_tcc.bat in the main dir to create zelda3.exe in that same dir
11. Configure with zelda3.ini in the main dir

Compiling on Windows with Visual Studio (4.5gb IDE and compiler)

Same Steps 1-7 above
8. Double-click Zelda3.sln
9. Change "debug" to "release" in the top dropdown
10. Choose "build > build Zelda3" in the menu to create zelda3.exe in the "/bin/release" subfolder
11. Configure with zelda3.ini in the main dir

Installing libraries on Linux/MacOS

1. Open a terminal
2. Install pip if not already installed

python3 -m ensurepip

3. Clone the repo and cd into it

git clone https://github.com/snesrev/zelda3
cd zelda3

4. Install requirements using pip

python3 -m pip install -r requirements.txt

5. Install SDL2

• Ubuntu/Debian sudo apt install libsdl2-dev
• Fedora Linux sudo dnf in sdl2-devel
• Arch Linux sudo pacman -S sdl2
• macOS: brew install sdl2 (you can get homebrew here)

Compiling on Linux/MacOS

1. Place your US ROM file named zelda3.sfc in zelda3/tables
2. Compile

make

Advanced make usage ...

make -j$(nproc) # run on all core
make clean all  # clear gen+obj and rebuild
CC=clang make   # specify compiler

Nintendo Switch

You need DevKitPro and Atmosphere installed.

(dkp-)pacman -S git switch-dev switch-sdl2 switch-tools
cd platform/switch
make # Add -j$(nproc) to build using all cores ( Optional )
# You can test the build directly onto the switch ( Optional )
nxlink -s zelda3.nro

More Compilation Help

Look at the wiki at https://github.com/snesrev/zelda3/wiki for more help.

The ROM needs to be named zelda3.sfc and has to be from the US region with this exact SHA256 hash 66871d66be19ad2c34c927d6b14cd8eb6fc3181965b6e517cb361f7316009cfb

In case you're planning to move the executable to a different location, please include the file tables/zelda3_assets.dat.

Usage and controls

The game supports snapshots. The joypad input history is also saved in the snapshot. It's thus possible to replay a playthrough in turbo mode to verify that the game behaves correctly.

The game is run with ./zelda3 and takes an optional path to the ROM-file, which will verify for each frame that the C code matches the original behavior.

Button	Key
Up	Up arrow
Down	Down arrow
Left	Left arrow
Right	Right arrow
Start	Enter
Select	Right shift
A	X
B	Z
X	S
Y	A
L	C
R	V

The keys can be reconfigured in zelda3.ini

Additionally, the following commands are available:

Key	Action
Tab	Turbo mode
W	Fill health/magic
Shift+W	Fill rupees/bombs/arrows
Ctrl+E	Reset
P	Pause (with dim)
Shift+P	Pause (without dim)
Ctrl+Up	Increase window size
Ctrl+Down	Decrease window size
T	Toggle replay turbo mode
O	Set dungeon key to 1
K	Clear all input history from the joypad log
L	Stop replaying a shapshot
R	Toggle between fast and slow renderer
F	Display renderer performance
F1-F10	Load snapshot
Alt+Enter	Toggle Fullscreen
Shift+F1-F10	Save snapshot
Ctrl+F1-F10	Replay the snapshot
1-9	run a dungeons playthrough snapshots
Ctrl+1-9	run a dungeons playthrough in turbo mode

License

This project is licensed under the MIT license. See 'LICENSE.txt' for details.