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: basic widescreen, shaders, 240 vertical res, hi-res mode7 map, MSU-1 audio, item switching, and over 30 bugfixes.

Building

You must self-build for now. Steps for 64-bit Windows:
(0) Download Python and install with "Add to PATH" checked
(1) Click the green button "Code > Download ZIP" on the github page and extract the ZIP
(2) Place your USA rom named zelda3.sfc in that folder
(3) Download TCC and SDL2 and extract each ZIP into the "third-party" subfolder
(4) Double-click "get_python_libs.bat" in the main dir.
(5) Double-click "extract_assets.bat" in the main dir. This will create zelda3_assets.dat.
(6) Double-click "run_with_tcc.bat" in the main dir. This will create zelda3.exe and run it.
(7) Configure with zelda3.ini in a text editor like notepad++

For other platforms and compilers, see: https://github.com/snesrev/zelda3/blob/main/BUILDING.md

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	Load a dungeons playthrough snapshot
Ctrl+1-9	Run a dungeons playthrough in turbo mode

License

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