RustyZooUser's Guide · pre-alpha edition, October 2026

RustyZoo

Zoo Tycoon (2001), on a new engine. Your own copy of the game, running natively on Windows, macOS and Linux.

An isometric zoo: a lion exhibit with trees and rocks, a picnic area, a crocodile pond and a crowd of guests on the paths.
Fig. 1Guests arrive at the lion exhibit. Drawn by RustyZoo from the game's own files, 16 October 2026.

Before you begin. RustyZoo is in early development and cannot be played from start to finish yet. Maps, the interface and building work today; animals, guests and staff are being brought to life now.

Chapter1

Welcome to RustyZoo

RustyZoo is an open-source engine for Zoo Tycoon, the 2001 game by Blue Fang Games. It is a new program, written in Rust, that reads the graphics, sounds, maps and animal behaviour from your own installation and plays them on today's computers, without compatibility settings or a Windows emulator.

The goal comes in two parts. First, the original exactly: the same rules, the same timing, the same zoo from the same saved game. Only once that holds comes an enhanced build, next to the faithful one: fixes for the original's known bugs, wide screens, larger zoos, and mods.

Familiar ideaOpenRCT2 does this for RollerCoaster Tycoon 2, and OpenTTD for Transport Tycoon Deluxe. RustyZoo follows the same path for the zoo.
Chapter2

A look around

Features are checked against the original game, picture against picture. Here is the same zoo and the same lion, once in each.

The original Zoo Tycoon: a lion exhibit with the Animal Information panel open for Lion 5.
Fig. 2.1The original game, 2001.
RustyZoo showing the same lion exhibit and the same Animal Information panel.
Fig. 2.2RustyZoo, 16 October 2026. The minimap and the date are not drawn yet.
A marine tank with a swimming animal beside a fenced path.
Fig. 2.3A tank and its swimmer.
The construction panel open over a grassy zoo with a fence and an exhibit gate.
Fig. 2.4The construction panel, as the original lays it out.
Rocky terrain, water and the zoo entrance with its stone walls.
Fig. 2.5Relief, water and the zoo entrance.
Chapter3

Getting started

  1. Have the game. Any installed copy of Zoo Tycoon: the full game (Complete Collection), or one of the two free trials Microsoft still hosts. RustyZoo ships none of the game's files.
  2. Download RustyZoo for your system. Not available yet: the first releases are planned for milestone M8.
  3. Show it where the game is, the folder that holds zoo.ini. RustyZoo reads everything it needs from there.

System requirements

Windows
Windows 11, 64-bit
macOS
One universal app for Apple silicon and Intel Macs
Linux
x86_64, as an AppImage and a Flatpak
Game data
Zoo Tycoon (2001), full game or free trial

Downloads coming soon. Nothing is released yet.

Chapter4

Development diary

Work started in early October 2026. The road is cut into ten milestones, M0 to M9. The dates are when each one closed.

  1. M0Foundations13 Oct 2026A window, an audio device, builds on Windows, macOS and Linux. 5 issues closed.
  2. M1Assets14 Oct 2026Reads the game's archives and file formats. 19 issues closed.
  3. M2Static world14 Oct 2026Draws every map as the original does: terrain, relief, paths, fences, buildings, animals. 23 issues closed.
  4. M3Window14 Oct 2026The game loop at the original's timing; scrolling, zoom, rotation, sound. 29 issues closed.
  5. M4UI15 Oct 2026Windows and buttons built from the original layout files, the main menu up to loading a map. 60 issues closed.
  6. M5Building15 Oct 2026Terrain, paths, fences, scenery, buildings and exhibits, and paying for all of it. 62 issues closed.
  7. M6Lifein progressAnimals, guests and staff, driven by the game's own behaviour scripts. 67 issues closed, 73 open.
  8. M7Full gamenextSaved games, research, scenarios, awards, translations.
  9. M8PackaginglaterReady-to-run releases for Windows, macOS and Linux.
  10. M9Beyond the originalafter parityThe enhanced build: bug fixes, wide screens, larger zoos, mods.
Chapter5

How it is built

RustyZoo is written by AI agents under the direction of one maintainer. The agents study how the original game behaves and how its files are made, write that down as specifications, and write the engine from those specifications.

The maintainer sets the course, makes every decision and tests the result against the original game, side by side. The comparison pictures are public, in the screenshots repository.

RustyZoo contains no code and no assets from the original game. The engine is written from specifications only, never from the original program's code.

Read how it is built, in detail

Chapter6

Questions and answers

Is this legal?
RustyZoo distributes none of the original files. It reads them from a copy you own, or from one of the free trials Microsoft still offers. It is not affiliated with or endorsed by Microsoft or Blue Fang Games.
Do I have to buy the game?
To try it, no: the two official trials, Zoo Tycoon and Marine Mania, are enough. For the full experience you need the full game.
Are the expansions supported?
Yes. The two expansions, Dinosaur Digs and Marine Mania, are supported: the engine reads their files.
Which computers will it run on?
Windows 11 (64-bit), macOS on Apple silicon and Intel, and 64-bit Linux.
Can I play it now?
Not yet. Milestone M6 aims at a freeform game you can play; downloads follow with M8.
Will it support mods?
Later. Mods are part of the enhanced build, after RustyZoo matches the original. The faithful build stays as it is.
Chapter7

Contributing and credits

Contributing

RustyZoo is open source under the GPL-3.0-or-later license. The code lives at github.com/RustyZoo/RustyZoo.

You do not need to write code to help. The most useful thing you can do is play the game on your own system and tell us what you find. If something crashes, looks wrong, or behaves differently from the original Zoo Tycoon, please open a GitHub issue. Screenshots help a lot, and so do the steps that led to the problem.

Pull requests are welcome. The repository has a CONTRIBUTING file that explains how to get started, so please read it before you open one.

There is no Discord server and no donation page for now. Questions, bug reports and ideas all go to the GitHub issues.

Credits and inspiration

RustyZoo stands on the work of many people and projects.

Zoo Tycoon was made by Blue Fang Games and published by Microsoft. RustyZoo is a fan project. It is not affiliated with, endorsed by or sponsored by either company. Zoo Tycoon and related names are trademarks of their owners.