Run functor in a project and it opens a workbench with your game on one side
and a coding agent on the other. The agent can see the running game: its state, its
frames, its inputs. So you can talk about what is on screen.
Describe it
Say what should change, in plain words.
The jump falls short. Make it clear the gap.
The agent edits
It reads the live game state and changes the code. It can press keys, step frames
and capture the picture to check.
The game reloads
The running game picks up the new code in place. No rebuild, no restart, and your
state survives.
Scrub to check
Pause, step a frame at a time, or drag back along the timeline and watch the moment
again.
Keep or revert
Read the diff, then keep the change or revert it. Each task is one change you can
undo.
The app is a preview, on macOS first, and is not in the prebuilt download yet. To try it
today, build it from source: npm run build:app && npm run build:cli,
then ./target/release/functor -d <project>.
It shows its work
When a run ends, the agent can open the lines it changed beside your work and step
you through them. It never moves your cursor or closes your tabs, and one click
puts your layout back.
Rewind before you decide
The transport bar under the game works like the web player's. Marks on the rail
show where you pressed a key and where the code reloaded, so the moment you care
about is easy to find again.
Bring your own agent
Claude Code or Codex, running with the settings you already use in the terminal.
A task is a conversation
Requests are listed as waiting on you, in progress or ready for review. A change waits
there until you keep or revert it.
The game stays in view
Put it in a pane beside the code, shrink it to a corner, or give it its own window.
Start from a template
Pick a starter or a complete example, describe the game you want, and the first task
starts with the project.
The same loop, headset on
Some changes have to be judged from inside the game. Functor reloads a running game
on a Meta Quest the same way it does on the desktop.
Works todayfunctor run vr runs your project on the headset and reloads it every
time you save, with an indicator in view.
In progress
Pairing with the desktop app over Wi-Fi: match a six-digit code, nothing to type in
the headset. Planned after that: describing a change while you play.
What the loop stands on
Instant Feedback
Edit your game while it runs. The runtime swaps your code under the live model. No
rebuild, no restart, no losing your place.
Travel Through Time
Rewind while editing, make changes, or extrapolate forward to see how your edits
ripple through gameplay.
Introspective
Read the live values moving through your game at any moment. The whole state is
plain data, so nothing is hidden from you or from an agent.
AI Native
The app is one client of an open door. Register functor mcp and any
coding agent, in any terminal, can launch, inspect, drive and rewind your game with
the same tools.
Batteries Included
Asset management, networking, physics, and spatial audio. In the box, ready to use.
Put the fun in functional programming.
How does it work?
Functor is a functional language built for game development, inspired by Elm and F#.
Pure functions, interpreted, no compilation. It lives in a Rust runtime that does the
heavy lifting: graphics and physics. Because a game is plain data and pure functions, it
can be reloaded, rewound and read, by you or by an agent.
