Tessarune — Let Your AI Agent Write Pixel Art as Code (Windows)

Tessarune is a pixel-art drawing language plus a production studio built for AI coding agents, with an interface for humans too. The agent writes the artwork as code (shapes, colours, named parts, joints, motion); Tessarune's engine renders the code into pixels. You keep both the images and the editable source.

No API key is required. Tessarune never contacts an external AI. Your own coding agent runs the Tessarune CLI on your PC. The agent and its subscription are not included. If an agent already writes your game's code, the same agent can make the art in the same project folder.

How it works

1. Brief: Pick a template and style in Studio, then collect size, actions, and references in a production brief.
2. Prompt: Paste the production prompt into your agent, which edits the artwork file and runs the CLI.
3. Preview: Studio shows source and artwork side by side and follows every save.
4. Refine: Refine colours and code yourself in Studio, or send notes to the agent.
5. Export: Export GIF, PNG, sprite sheet + JSON, or PNG frame sequences.

Why code instead of image generation

No image-generation model is involved. Treating pixel art as code solves core consistency and editing problems:

• Editable forever: Named parts, palettes, joints, and motions remain completely editable.
• Deterministic: Same source + seed + settings + engine version = same pixels. Re-rendering costs no AI usage.
• True pixel canvases: A 64×64 design is a real 64×64 grid.
• Resampled motion: "More frames" means resampling motion at more time steps, not duplicating images.
• 3D joints: 3D joints inside small sprites allow arms to reach forward, legs to pass behind, and parts to overlap by depth.
• Consistent cast: A manikin-first procedure builds human figures from three numbers so a cast shares proportions.

What's in the box

• Studio: Local browser app with library, split view, motion editor, frame notes, history with accepted versions, checks for flicker, missing pixels, and required actions, value studies, and export presets.
• JSON CLI: CLI for agents with AI-start manuals and structured briefs.
• Rendering engine: Two bundled runtimes (0.3.0 and 0.4.0) so older work draws the same picture.
• Manuals and assets: 25 production manuals in English and Japanese, templates, style profiles, and editable examples.
• Windows builds: Setup installer and a portable version for Windows 11 x64. No separate Node.js install.

The art on this page

The art on this page and the studio's asset packs were drawn this way:

• Arcane Curiosities
• Dungeon Mechanisms
• Millreach
• Ashveil

Honest notes

Tessarune is not a one-sentence image generator. Tiles, effects, and backgrounds come out cleanly, but human figures need a few rounds. The review, history, and notes tools exist for those rounds.

You don't need the most expensive model—any agent that can edit files, run commands, and look at an image works. An ordinary chat window cannot drive it directly, though you can paste code into Studio yourself.

No MP4 export, no FBX/glTF export, and no engine-specific importers. The sprite-sheet JSON has every number an importer needs.

The Windows executables are unsigned, so SmartScreen may warn. SHA-256 checksums are included in the download.

License and updates

What you make is yours to sell. You have commercial use, editing, publication, and sale rights for images, animation, video, and artwork code you create, with no revenue share. One purchase covers one person on devices they control. No redistribution of the application, engine, or manuals. The full EULA (English and Japanese, Japanese authoritative) is in the download.

Future Tessarune releases are free for buyers of this itch.io page and appear here as new downloads (the itch app can update them). No release schedule or feature promise. For support, ask questions and report bugs in the comments on this page, with your version and what happened.

Specs

• Version: 1.3.0 (2026-09-20)
• Platform: Windows 11 x64 only (one-time purchase, no subscription, no account, no activation)
• Download: About 61 MB
• Languages: UI, CLI, and manuals in English and Japanese
• Outputs: PNG, GIF, sprite sheet + JSON, PNG frame sequences
• Official site: https://tessarune.dev

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More from Aurum Nocturne

• Arcane Curiosities — animated pixel props, Godot-ready
• Dungeon Mechanisms — animated traps, doors & switches
• Sprite Sheet Kit — free: GIF → sprite sheet + Godot SpriteFrames, in your browser