Understanding what happens under the hood makes you better at prompting, debugging, and reading your usage ledger. Here’s the rundown.

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An agent, not templates

When you send a prompt, Tesana doesn’t fill in a template or retrieve a pre-made game. It hands your request to a real AI agent that works on your project the way a human developer would. Tesana picks the model for every run, so you always get the one it trusts most for the job.
  1. Reads your project. The agent re-reads your game’s code, assets, and recent history to understand the current state. This is why context grows with your project — and why caching that context matters so much for cost.
  2. Plans. For new games and big changes it works out an approach first — and in Plan mode it shows you that plan before building.
  3. Writes real code. The agent writes and edits the game’s TypeScript — gameplay, scenes, shaders, UI, and configuration. This is genuine source code you can read in the built-in editor and export.
  4. Makes the look and sound. Visuals, effects, and audio are built to match your art direction; reference images steer this, and your own files can be imported.
  5. Builds and checks. Every build is type-checked, bundled, and booted in a real browser before it reaches you. When a check fails, the agent reads the error and fixes its own mistakes.

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Why builds take minutes

A build is a long agent session: many read-think-write-check cycles. A complete first build typically takes several minutes to a few tens of minutes; small edits are much faster. The progress feed in the chat panel shows what the agent is doing in real time.

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Plan turns vs build turns

Two kinds of turns show up in your chat:
  • Plan turns — the AI thinks and proposes; no game files change. Cheap.
  • Build turns — the AI actually modifies your game. This is where the real work (and the bulk of credit usage) happens. Each committed build becomes a version you can revert to.
A Loop is a chain of build turns the AI runs on its own, improving the game until the credit budget you set is used.

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Built on the open web

New games are standard web games:
  • 3D games use Three.js, the most widely used 3D library on the web, with real-time physics.
  • 2D games use Phaser, a mature 2D game framework.
  • Everything is written in TypeScript and bundled with Vite.
Consequences you’ll appreciate later:
  • Games run in any modern browser — desktop or phone — with nothing to install.
  • The code editor in the Studio shows the real project files.
  • Exports are standard builds: a static web build, desktop apps, and the full TypeScript source project. Your game is never locked to Tesana. See Exports.
Games created before Tesana moved to the web engine were built on the Godot engine. They keep working and can still be edited, played, and exported; new games are always built on the web engine.

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What this means for you

  • Iterate in small steps. Agents excel at focused changes and struggle with “build my entire dream game in one prompt” — exactly like human developers.
  • Specificity wins. The agent acts on what you say, not what you meant. See Prompting.
  • Cost tracks work. Long sessions on big projects do more work. The Usage page shows what each prompt cost.