Animal Forest Decomp: 18.51 Percent and a Japan-Only ROM

By Indie Kings | October 29, 2026

Updated October 29, 2026: zeldaret/af, the decompilation of the Nintendo 64 game Animal Forest, reports 18.51 percent of code matched for the Japanese release and has not merged a change since August 16, 2026. The repository has 302 stars, 30 forks, 16 contributors and a CC0 license, and it builds exactly one ROM from a base copy the user must supply.

Image: a Nintendo 64 console, the platform Animal Forest shipped on, via Wikimedia Commons.

The game that stayed in Japan

Animal Forest, or Doubutsu no Mori, is the Nintendo 64 original of the series that became Animal Crossing. It shipped in Japan in April 2001, late in the console's life, and it never left the country. The GameCube version was localized and expanded into the game most Western players know, which makes the N64 release a genuinely different artifact: smaller, rougher, and built around the memory and cartridge constraints of 2001. That is exactly the kind of software decompilation is for, because emulation can run it but only a source tree can explain it.

The project is one of several under the zeldaret umbrella, and it follows the same conventions as the Zelda decompilations covered on this site. The repository takes a Nintendo 64 ROM, extracts its assets, combines them with C code reverse engineered from the binary, and produces an identical ROM. The README is careful to define what that is not: the project is not a port to PC or any other platform, and using it as the basis for a port or a commercial product is an explicit non-goal. That sentence exists because decompilation projects are frequently mistaken for source ports, and the distinction matters for how the work is judged and licensed.

Only the Japanese version is supported, which keeps the scope honest. There are no regional variants, no demo builds and no later revisions in the support matrix, just the one cartridge and its one hash. For a game that never received an international release, that is the only sensible target, and it means the project does not spend effort on the version matrix that a game like Twilight Princess requires.

What 18.51 percent buys

The progress badge, served from progress.deco.mp, reports 18.51 percent for Japanese code. That figure places the project in the early middle of the decompilation curve: enough functions are named and rewritten that the code is useful to read, but far from the point where the tree compiles into a matching ROM without large gaps. The practical value at this stage is documentation. Named functions, recovered structures and a readable implementation of game systems are useful to romhackers, to researchers studying how the game stores its town data, and to anyone working on the later Animal Crossing decompilation who wants to compare implementations.

Activity has paused. The newest commit is dated August 16, 2026 and is titled Generate decomp.dev progress reports, which is infrastructure work rather than game code, and before that the repository had been quiet for some time. Six issues are open. Sixteen contributors over three and a half years is a small group, and the project was created in March 2023, which means the pace has always been modest rather than suddenly declining. Decompilations of Japanese-only N64 titles have a smaller contributor pool, because the pool of people who can read the game's text and the pool of people who can read MIPS assembly overlap less than either group would like.

That overlap is also the project's advantage. Documentation of a Japan-only game is scarce, so a matching source tree becomes a primary source. The README links the GameCube decompilation separately, which is a useful pointer: the two projects cover related codebases, and someone comparing them can see what changed when the game moved to a disc-based console with more memory and a wider release.

A build that refuses to be a port

Building requires a legally obtained ROM placed at baseroms/jp/baserom.z64. The toolchain is standard for N64 decompilation: make, git, build-essential, clang, the MIPS binutils package, Python 3 with venv, then make venv, make setup, make extract, make, and make compress. The build extracts assets from the base ROM and links them with the reconstructed C, which is why the repository can be public without containing any game data. Without the ROM, there is nothing to build.

The license is the most permissive in this series. The src and include folders are CC0 as far as possible, and the rest of the repository is CC0 unless a file says otherwise. Subrepositories keep their own licenses, including asm-differ, asm-processor, fado, ultralib and z64compress, which is a normal arrangement for a project assembled from community tooling. CC0 matters because it removes ambiguity for anyone who wants to reuse the reconstructed code in their own project, which is not true of the LGPL and AGPL projects elsewhere in this survey.

The README's warning block is the usual one: the codebase is a work in progress, it can change drastically, and some parts of the ROM may not be shiftable, which makes certain modifications difficult. That last word is specific to matching decompilation. Shiftability means the code can be moved without breaking absolute references, and a ROM that is not fully shiftable constrains what a modder can insert or expand. For a project at 18.51 percent, much of the ROM is still in that category, and the warning is the honest description of the current state rather than a formality.

Project card

FAQ

What is zeldaret/af?
A work in progress decompilation of Animal Forest, the Japan-only Nintendo 64 game that preceded Animal Crossing.

Does it include the game?
No. It contains no assets or ROM data, and you must supply your own copy as baserom.z64 to build it.

How complete is it?
The progress badge reports 18.51 percent of code matched, so large parts of the game remain undocumented.

Is it a PC port?
No. The README says it is not a port and that porting is an explicit non-goal. It produces a matching Nintendo 64 ROM.

Why only the Japanese version?
Animal Forest was never released outside Japan, so there is no other regional build to support.

Can I reuse the code?
The src and include folders are CC0 as far as possible, which makes reuse unusually straightforward, though bundled tools have their own licenses.

Bottom Line

At 18.51 percent and with no commits since August, this is not a project to watch for a finished ROM. It is a project to read. The Japan-only status makes it the closest thing to an authoritative source for the original Animal Forest, and CC0 licensing makes the recovered code genuinely reusable in a way that most decompilations are not. The single target and the clear non-goal statement keep it honest about scope. For anyone studying the series' origins or the N64's late software, it is a small, well organized archive that deserves more contributors than it has.

Sources

• GitHub zeldaret/af README, project scope, setup steps and licensing, accessed October 29, 2026
• progress.deco.mp badge data for Animal Forest Japanese code, accessed October 29, 2026
• GitHub API metadata for zeldaret/af, stars, forks, contributors, issues and latest commit, accessed October 29, 2026

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