OpenZT2

An open-source reconstruction of
the classic zoo sim.

Coming in Q4 2026 —
Join the Discord to
follow our progress!

Join the Discord discord.gg/5E7xxYAr
Screenshot by MF217 O — Original game. This screenshot was captured in Zoo Tycoon 2.

Development roadmap

Four phases connect the original game to OpenZT2. Each phase has its own record and measure of progress.

Phase 1

Disassembly and decompilation

Executable addresses, byte ranges, and symbols.

Done100%
Explore the byte map → Phase 2

Reverse engineering

Recovered identities, boundaries, and behavior evidence.

Done100%
Explore the binary perimeter → Phase 3

Asset conversion

Original content formats and their conversion coverage.

19 of 19 families done100.0%
Explore asset conversion → Phase 4

Gameplay reimplementation

Functional capabilities across the gameplay domains.

145 of 163 capabilities done89.0%16 not done · 2 blocked
Explore gameplay progress →

What’s new in OpenZT2?

  • Mod hot reloads

    Reload mods from the main menu without restarting the game and moving files around.

  • 64-bit platform

    Native 64-bit targets, including Linux and macOS.

  • Modern shader pipeline

    A custom D3D9 Effects framework transpiler produces WGSL and WebGPU pipeline assets on the fly for absolute authenticity to the original.

  • Rust + Bevy performance

    Performance improvements powered by the Bevy engine in Rust. The custom game currently contains about 200 thousand lines of code, excluding third-party dependencies.

Getting started

  1. Get OpenZT2

    Available at release.

  2. Select your game files

    Point OpenZT2 to your Zoo Tycoon 2 files.

  3. Start playing

    Launch and build the zoo of your dreams.

System requirements Supported editions Compatibility & known issues

Pixel comparisons guide the work on OpenZT2’s shader and material pipeline. These comparisons show the world-selection globe, main menu and terrain at different stages of development.

O · Original on the left, N · OpenZT2 in the centre, and an amplified pixel-difference heatmap on the right. Brighter magenta marks larger differences. The changed-pixel count includes the entire screen, including text and layout.

Original and OpenZT2 world-selection globes with blue oceans, land, clouds and orange flags, beside the pixel-difference heatmap.

Globe textures and layered materials

The Earth surface, clouds and orange flags now render together. The earlier build showed a white sphere. Cloud shading and the selected-location marker still differ.

View full-size comparison →
Before the globe material corrections
Earlier comparison: the original textured globe beside OpenZT2’s untextured white sphere and a difference heatmap.
The earlier capture of the same world-selection checkpoint. Material projection, lighting and draw-order corrections restored the Earth’s appearance.
Original and OpenZT2 grassland-filtered globes with American Prairie selected, followed by the pixel-difference heatmap.

Biome shading and lighting

The filtered globe retains its blue ocean and green grassland highlight after its material changes. Cloud appearance, marker placement and text wrapping remain visible differences in this capture.

View full-size comparison →
Original and OpenZT2 main-menu panels with their buttons and profile controls, followed by a difference heatmap. Both menus display the original Zoo Tycoon 2 logo, with different backgrounds.

Main-menu layout and controls

The authored logo, panel, buttons and profile controls retain the original menu’s familiar layout. Different backdrops and OpenZT2’s additional archive controls contribute to this full-screen difference.

View full-size comparison →
Original and OpenZT2 overhead terrain with grass, dirt, slopes and the gameplay HUD, beside the pixel-difference heatmap.

Terrain textures and material balance

Grass, dirt and slopes render through the restored material pipeline. Texture detail, colour balance and lighting still differ. Camera framing and foliage placement also vary, so this heatmap includes more than material differences.

View full-size comparison →

Made for players
and creators

OpenZT2 is designed to be mod-friendly and easy to extend. Build new content, improve the game, and share your ideas with the community.

Screenshot by MF217 O — Original game. This screenshot was captured in Zoo Tycoon 2. Two giant pandas playing in their exhibit as visitors watch in Zoo Tycoon 2.

Coming Q4 2026

Follow development on Discord.

A roaring Tyrannosaurus with a visitor tumbling overhead in Zoo Tycoon 2. Screenshot by MJ O — Original game. This screenshot was captured in Zoo Tycoon 2.
Screenshot by MF217 O — Original game. This screenshot was captured in Zoo Tycoon 2.

Help OpenZT2 grow

Join a friendly community of players and developers making OpenZT2 better every day.

Join the Discord Contribute
A gorilla beside a carved stone shelter in Zoo Tycoon 2. Screenshot by MF217 O — Original game. This screenshot was captured in Zoo Tycoon 2.